JPH0767314B2 - Drive control method for stepping motor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor drive control method, and more particularly to a stepping motor drive control method for driving a carriage drive mechanism of a serial printer.

[Technical background of the invention]

In many serial printers, print position control is performed by reciprocating the carriage on a slide guide by a carriage drive mechanism that connects a carriage on a slide guide to a stepping motor using a timing belt or a wire.

In the drive mechanism, in order to improve the printing speed, it is necessary to start or stop the carriage in a short time, and to speed up the rise of the current flowing in the winding of the motor,
In order to improve the high-speed characteristics, it is general to drive the motor at a timing as shown in FIG. 5 by using a drive circuit of dual power source drive system as shown in FIG. Therefore, when the gap between the slide guide and the moving bearing of the carriage that is a pair with the slide guide is large, or when the tension of the timing belt or the wire is small, a mechanical error between the carriage and the stepping motor is large, Since the operation of the motor and the carriage are often inconsistent with each other, vibrations of the carriage are generated at the time of starting and stopping the motor, and a problem such as audible impact noise is likely to occur. In particular, when the vibration of the carriage generated at the time of start continues until the print start time, the print position may be displaced from the normal position, and the print may be distorted.

[Prior Art of the Invention]

Conventionally, various methods have been attempted as measures for preventing vibration in the drive mechanism. First, as a measure from the mechanical aspect, the gap between the moving bearing of the carriage and the slide guide is reduced to make it difficult to vibrate. In order to match the method and the operation of the stepping motor and the carriage, the tension of the timing belt or the wire is increased so that the connection between the drive shaft of the motor and the carriage is made as elastic as possible. The former has drawbacks such as difficulty in maintaining processing accuracy and high cost, and the latter has a limit in increasing the tension because driving torque increases with increasing tension and power consumption of the motor also increases. There is a drawback of.

Next, as a measure from the control side, in order to make the stepping motor rise smoothly, for example, the normal step angle of the stepping motor called mini-step drive is divided into minute parts and the torque fluctuation with respect to the motor drive shaft is divided. There is also known a driving method for performing smooth rotation with less power consumption. In this driving method, the step angle is divided in order to increase the smoothness in addition to the high cost due to the complexity of the driving circuit and software. However, there are drawbacks such that the high-speed characteristics deteriorate and the printing speed decreases.

[Object of the Invention]

The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a drive control method for a stepping motor that can prevent vibration of a carriage by using a plurality of different voltage power supplies in an excitation section.

Example of Invention

Hereinafter, the present invention will be described in detail with reference to Examples.
The figure is a conventional two-phase excitation-2 power source drive type stepping motor drive circuit diagram. M is a stepping motor A,
B is a winding of the motor, and one ends of the windings A and A are connected to each other and connected to the collector of the transistor TRAC and the cathode of the diode DA. The winding B
One ends of and are similarly connected and connected to the collector of the transistor TRBC and the cathode of the diode DB. On the other hand, the other ends of the windings A, B are connected to the collectors of the transistors TRA, TR, TRB, TR, respectively. Further, the emitters of these transistors are connected to the OV potentials of the power supply VL and the power supply VH, the anodes of the diodes DA and DB are connected to each other and connected to the power supply VL, and the emitters of the transistors TRAC and TRBC are connected to each other and are connected to each other more than VL. Connected to high voltage power supply VH.

Therefore, the winding is excited by the excitation control signals PA, P, PB, P input to the bases of TRA, TR, TRB, TR, and the voltage control signal COMA input to the bases of TRAC and TRBC. The voltage applied to the winding can be varied between VH and VL by and COMB.

FIG. 2 shows a conventional control circuit for controlling the drive circuit of FIG. 3, in which 1 is a transistor TRAC and TR.
A voltage controller 2 for controlling the voltage applied to the winding of the motor M by controlling BC, an excitation controller 2 for controlling the transistors TRA, TR, TRB, TR according to the excitation sequence of FIG. Voltage control unit 1 and excitation control unit 2
Is a driver unit for amplifying the output signal of the motor. The motor is rotated according to the excitation sequence of FIG. 4 by a predetermined drive control method, and at the same time, the voltage applied to the winding of the motor is controlled. Be done.

FIG. 1 shows an embodiment of the present invention and is a timing chart diagram of drive signals in the control circuit diagram of FIG. 2 and the drive circuit diagram of FIG. 3 when the present invention is implemented.
When drive pulses T1 to T4 indicating the drive timing are input to the control circuit, the excitation control signal PA from the rising edge of T1 to the rising edge of T3 and the excitation control signal from the rising edge of T2 to the rising edge of T4 according to the excitation sequence of FIG. PB
Excitation control signal P from the rise of T3 to the rise of T1
However, the excitation control signal P is generated from the rising of T4 to the rising of T2, and the voltage is applied to the winding A, the winding B, the winding, and the winding only during the generation period of the signal.
VL is applied. That is, each of the excitation control signals PA, PB, P, and P is repeatedly turned on and off by a quarter cycle with one cycle of four drive pulses T1 to T4, and a drive voltage of a low voltage VL is supplied. Is a timing signal for. On the other hand, at the same time, the voltage control signal COMA that rises from the rising edge of T2 and T4, falls to the center of the rising edge of T2 and T3 from T2, and to the center of the rising edge of T4 and T1 from T4 respectively. T1 and
Rising from T3 rising, and from T1 T1 and T2
The pulse of the voltage control signal COMB that falls to the center of the rise of T3 and the center of the rise of T3 and T4 respectively from T3 occurs, and when the former occurs, the excitation control signals PA and P Within the generation period, the winding A
The high voltage VH is applied to and, and when the latter occurs, the high voltage VH is applied to the winding B and within the generation period of the excitation control signals PB and P, respectively.

The generation period of the voltage control signals COMA and COMB is T1.
And rises with a delay of 500 μsec or more from the rise of T3, and at the latest from T1 until the rise of T3,
The period from T3 to the rise of T1 respectively, and the latter is 500 μs from the rise of T2 and T4.
Start up with a delay of ec or more, and at the latest from T2, T4
It is optional within the period of falling by the rising edge of, and from T4 by the rising edge of T2.

That is, both voltage control signals COMA, COMB fall at least within a half cycle of the excitation control signals PA, PB, P, P, and the former of the two voltage control signals COMA, COMB is the above excitation signal. The control signals PB and P rise from drive pulses T2 and T4 that are the starting points at the time of rising and falling. On the other hand, the latter is the excitation control signals PA, P
Drive pulse that is the starting point at the rising and falling edges of
Of T1 and T3, it rises after the third excitation switching according to the drive timing.

In this way, the winding of the stepping motor is excited according to the excitation sequence, and the excitation voltage is switched from VL to VH within the excitation section of the excitation, thereby connecting the motor to the carriage drive mechanism. In this case, the electric energy is supplied to the motor stepwise, so that the vibration to the carriage can be drastically reduced.

Essentially, the motor rotates by supplying the excitation voltage as VL to the windings that are in parallel with each other in response to the excitation control signals that are shifted by a quarter cycle. And conventionally,
In order to improve high-speed response, the voltage control signal synchronized with the rising edge of the excitation control signal sets the excitation voltage to a high voltage VH for a short time from the start of excitation, and the excitation voltage is lowered after the lapse of that short time. The voltage was VL. However, although this improves the high-speed response, an impact noise is generated at the start of driving.

By the way, among the windings that are parallel to each other, the leading one of the windings having the preceding excitation section is one quarter cycle after the start of the excitation. A voltage control signal that rises for a short time after this quarter cycle has been conventionally used, and this voltage control signal has conventionally been used to increase the excitation voltage for a short time from the start of excitation in the subsequent excitation interval. It was voltage.

In the present invention, the exciting voltage is made high from the middle of the preceding exciting section by using the voltage control signal which rises for a short time at the rising of the subsequent exciting section. That is, when a certain voltage control signal is used conventionally, the voltage control signal for the winding in the subsequent excitation section is diverted to the winding in the preceding excitation section, so it is possible to configure without adding new equipment. There is an effect that can be.

The timing at which the high voltage VH is applied to the winding is preferably 500 μsec or more from the rise of the excitation section and 500 μs.
Experimental results were obtained that it was not so effective when it was less than ec.

〔The invention's effect〕

As described above in detail, according to the present invention, the excitation voltage applied to the winding of the stepping motor is switched from the low voltage to the high voltage after a predetermined time from the start-up in each excitation section in which the excitation is sequentially performed. As a result, it is possible to provide a drive control method of a stepping motor that can prevent vibration of the carriage at high speed, low cost, low power consumption, high processing accuracy, and without using a complicated drive circuit and software. effective.

[Brief description of drawings]

FIG. 1 is a timing chart of a drive signal showing an embodiment of the present invention, FIG. 2 is a conventional control circuit for controlling the drive circuit of FIG. 3, and FIG. 3 is a conventional two-phase excitation- FIG. 4 is an excitation sequence diagram for exciting the motor, and FIG. 5 is a timing chart diagram of a conventional drive signal.

Claims (1)

[Claims] 1. A current is supplied from two different voltage power supplies having different voltage values, two phases are selected from a plurality of winding phases in a predetermined excitation sequence in accordance with a drive timing, and the two phases are sequentially excited. In the drive control method of the stepping motor by the dual power supply drive method that changes the voltage applied to the winding by switching the power supply in each excitation section, the next excitation section according to the drive timing is A low voltage is applied to drive until start-up, and the drive at the time of startup is performed.In addition, in the excitation interval in which the excitation is sequentially performed according to the excitation sequence, the voltage applied to the winding is applied, and the low voltage is applied at the time of start-up. After a lapse of time from the start of the section to the arrival of the next excitation section according to the drive timing, the voltage is switched from low voltage to high voltage and applied to reduce the high voltage. Also, the drive control method of the stepping motor, wherein the drive is continued by returning to a low voltage before the fall of the excitation section.