JPH0491699A - Drive for pulse motor - Google Patents

Abstract

PURPOSE:To flatten torque-frequency characteristics, and to prevent the generation of vibrations, noises and heat generation resulting from over-torque in a low speed region by changing the two-phase excitation time of an excitation signal in response to the frequency of the excitation signal fed to a pulse motor. CONSTITUTION:A drive 10 is composed of a line memory 11 for storing a printing data output from a facsimile device 15, an excitation-signal forming circuit 12 forming an excitation signal corresponding to the printing data stored, and a driver circuit 13 supplying each exciting coil of a pulse motor 14 with currents in response to the excitation signal output from said excitation-signal forming circuit 12. The excitation-signal forming circuit 12 determines a proper line drive period from the printing data stored in the line memory 11, and decides the length of the time when two phase are excitated simultaneously for one period, the specified two-phase excitation time. When the line drive period is 5ms, the one-phase excitation time is zero, and two-phase excitation is acquired substantially, thus obtaining large torque.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an apparatus for exciting and driving a pulse motor.

[Prior Art] As a drive method for a pulse motor, a two-phase excitation method and a 1-2 phase excitation method are generally used. The former is, for example, when a pulse motor consists of four-phase excitation coils of coil A to coil D, AB, BC, and C as shown in FIG. 2(a).
This method always excites two phases in duplicate, such as D and DA. On the other hand, the latter is a method in which two-phase excitation and one-phase excitation are alternately repeated in the order of A, AB, B, BC, C, CD, D, and DA, as shown in Figure 2 (b). It is.

If both are driven with the same timing pulse, the rotation speed in two-phase excitation will be twice the rotation speed in one-two phase excitation. Therefore, 2-phase excitation is used for high-speed operation, and 1-2-phase excitation is used for low-speed operation. In addition, pulse motors have a characteristic that their torque is large in the low speed range, but as the pulse frequency is increased and the rotational speed is increased, the torque decreases. This will serve as the selection criteria.

[Problems to be Solved by the Invention] Devices equipped with pulse motors selected based on such criteria generate vibration and noise due to overtorque in low speed ranges, and the torque in high speed ranges is lower than the required torque. Since the motor is equipped with a large pulse motor in order to prevent the voltage from falling below , the size is large and the manufacturing cost is high.

The present invention was made in view of the above problems, and its purpose is to prevent the generation of vibrations and noise in low speed ranges,
Another object of the present invention is to provide a pulse motor drive device that allows the use of a small-sized pulse motor.

[Means for Solving the Problems] The object of the present invention is to provide a pulse motor drive device that excites a pulse motor using a 1-2 phase excitation method, which controls the rotational speed of the pulse motor according to data received from the outside. means for generating an excitation signal having a frequency corresponding to the set rotational speed and a two-phase excitation time having a length corresponding to the rotational speed; and the generated excitation signal. This is achieved by a pulse motor drive device characterized by comprising: means for supplying a current corresponding to the current to the excitation call of the pulse motor.

When the rotational speed of the pulse motor is set according to external data, an excitation signal having a two-phase excitation time corresponding to the rotational speed is generated. Typically, this excitation signal is
It is a pulse-like signal in which the two-phase excitation time becomes longer as the rotation speed increases.

As a result, the torque-frequency characteristics of the pulse motor are flattened, and overtorque in the low speed region is eliminated.

[Example] An example of the present invention will be described below with reference to the drawings.

In FIG. 1, 15 is a facsimile device, 14 is a pulse motor for feeding paper in a recording mechanism that prints with a thermal head, and 10 is a 1-2 phase motor that drives the pulse motor 14 according to print data output from the facsimile device. This is an excitation type pulse motor drive device.

The driving device IO is a line memory II for storing print data output from the facsimile device I5.

From an excitation signal generation circuit 12 that generates an excitation signal according to stored print data and a drive circuit 13 that supplies current to each excitation coil of the pulse motor 14 according to the excitation signal output from the excitation signal generation circuit 12. Become.

The excitation signal generation circuit 12 determines an appropriate line drive cycle from the print data stored in the line memo January 1, and further determines the length of time during which two phases are simultaneously excited during one cycle according to the table below, i.e. , determine the two-phase excitation time.

As shown in the table above, the faster the pulse motor rotates, that is, the shorter the line drive period, the longer the two-phase excitation time becomes.

Particularly, when the line drive cycle is 5 ms, the one-phase excitation time becomes zero, which essentially results in two-phase excitation, so that a large torque can be obtained.

In this way, by increasing the two-phase excitation time of the excitation signal as the rotational speed of the pulse motor increases, the decrease in torque in the high-speed region is compensated for, and the torque characteristics are flattened.

This eliminates overtorque in the low speed range, prevents noise and heat generation, and makes it possible to reduce pitch irregularities in printing.

[Effects of the Invention] The pulse motor drive device of the present invention changes the two-phase excitation time of the excitation signal supplied to the pulse motor according to the frequency of the excitation signal, so that the torque-frequency characteristic is flattened and the low speed Vibration due to overtorque in the area,
It is possible to prevent noise and heat generation. Furthermore, since the torque in the high speed range is improved, it becomes possible to use a smaller pulse motor.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment in which the pulse motor drive device according to the present invention is applied to a facsimile machine, and Fig. 2 is a time diagram for explaining the 1-2 phase excitation force type and the 2-phase excitation force type of the pulse motor. It is a chart. 10...Pulse motor drive device, 11...
... line memory, 12 ... excitation signal generation circuit, 13 ... drive circuit, 14 ... pulse motor, 15 facsimile device.

Claims (1)

[Claims] A pulse motor drive device that excites a pulse motor using a 1-2 phase excitation method, and has means for setting the rotation speed of the pulse motor according to data received from the outside, and a frequency corresponding to the set rotation speed. means for generating an excitation signal having a two-phase excitation time having a length corresponding to the rotational speed; and means for supplying a current corresponding to the generated excitation signal to an excitation coil of the pulse motor. A pulse motor drive device comprising: