JPH10191694A - Drive circuit for stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the malfunction of a stepping motor by a method wherein, on the basis of a rotation designation clock, a phase current by which the stepping motor is turned is generated in such a way that the rise of a plurality of clock pulses is synchronized with a microstep ticked by the stepping motor and the phase current is supplied to the stepping motor. SOLUTION: Mode designation signals M1, M2, M3 and a rotation-start-time designation pulse PO are input to a clock generator 13 inside a driver 12, and a rotation designation clock CK11 is generated here so as to be output to a phase-current generation part 14. The rotation designation clock CK11 is generated in such a way that a first clock rises in synchronization with the rise of the rotation-start-designation pulse PO. The phase-current generation part 14 generates a phase current Io regarding the rotation of a stepping motor M on the basis of the rotation designation clock CK11, the phase current Io which agrees with a rotation state designated by the rotation designation clock CK11 is supplied to the stepping motor M, and the stepping motor M is turned by a prescribed angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving circuit for a stepping motor, and more particularly, to an improvement of a driving circuit for microstep driving a stepping motor used in a printer or a copying machine.

[0002]

2. Description of the Related Art A conventional driving circuit for a stepping motor will be described below with reference to FIG. This circuit includes a CPU 1 and a driver 2 and drives a two-phase excitation stepping motor M as shown in FIG.

According to the above circuit, first, a control signal SS1 for instructing a driving state such as a rotation speed of a stepping motor and an excitation mode is input to a CPU. This allows two phases,
The CPU 1 stores information as to whether any one of the excitation modes of the 1-2-phase, W1-2-phase, and 2W1-2-phase excitation is selected, information on the time of starting rotation, and how many times the stepping motor M is rotated. Recognized by

Next, mode designating signals M 1, M 2 and M 3 for instructing the excitation mode are generated in the CPU 1 and output to the driver 2. Thus, the driver 2 selects which excitation mode to drive the stepping motor, and recognizes that the stepping motor is driven in, for example, 2W1-2 phase. At the same time, a rotation designation clock C related to the rotation of the stepping motor M
K1 is generated and output to the driver 2. The rotation designation clock CK1 is a clock for rotating the stepping motor M by a predetermined angle in synchronization with the rise.

As shown in FIG. 4, the frequency of the rotation designation clock CK1 differs depending on the excitation mode, and there is only one clock CK1 in two phases during the same cycle T0, but there is only one clock CK1 in 2W1-2 phases. 8 times clock CK
1 and the clock frequency is eight times higher. Therefore, each time the excitation mode is switched, the CPU 1 needs to switch the clock frequency.

The driver 2 generates a phase current Io for driving the stepping motor M based on the rotation designation clock CK1 and the mode designation signals M1, M2, M3,
By supplying to the stepping motor M, the stepping motor M rotates by a predetermined angle in synchronization with the rise of the rotation designation clock CK1 in the designated excitation mode.

FIG. 5 is a diagram showing the relationship between the actual engraving step of the motor and the excitation mode. One rotation (36 in FIG. 5)
(0 ° rotation) is the actual rotation angle of the stepping motor.
It corresponds to 2 °. Usually, the stepping motor rotates in a step of origin → origin shown in FIG. That is, for example, when considering the counterclockwise rotation in the 2W1-2 phase, the motor stopped at the origin O1 rotates to the next origin O2 and stops at O2 while cutting eight steps thereafter, and stops again at O2. To the origin O3. The eight steps engraved at this time are the above-described rotation designation clock CK1.
It will be engraved in synchronization with the rising edge of.

The origin and the next appearing origin (for example, O1 and O
The angle with 2) is 90 ° in FIG. 5, but as described above, one rotation (360 ° rotation) in FIG. 5 corresponds to the actual rotation angle of the stepping motor of 7.2 °. Is converted to the actual rotation angle of the stepping motor.
This corresponds to a rotation of 8 °. Since the actual motor repeats rotation / stop for each step, this 1.8 ° is referred to as a basic step angle θs.

FIG. 6 is a table showing, for each phase excitation mode, the number of rotation designation clocks CK1 required until the stepping motor rotates 360 ° actually. As shown in this table, the basic step angle is 1.8 ° in driving a two-phase stepping motor, and 200 ° in two-phase excitation.
400 for 1-2 phase excitation, 800 for W1-2 phase
1,600 for 2W1-2 phase, 3 for 4W1-2 phase
As many as 200 clocks CK1 are required.

[0010]

However, according to the above-mentioned conventional driving circuit as shown in FIG. 5, the following problems occur. The rotation designation clock CK1 is
All are generated by the CPU 1 as software. Although the original function of the CPU 1 is to control the drive circuit, when the stepping motor M is rotating, the CPU 1 almost operates to generate the rotation designation clock CK1.
Will be overburdened.

That is, at the time of low-speed rotation such as two-phase,
While the rotation designation clock CK1 is being generated, other jobs can be processed by interrupt processing, for example, 4W1-2.
In the case of the phase, as described above, a high-speed clock CK1 requiring as many as 3200 clocks per rotation is generated. In such a case, interrupt processing of another job is practically impossible. Inconvenience that the CPU operates almost exclusively for generating the clock occurs, and in severe cases, the processing of another job is delayed and the rotation position of the stepping motor may be shifted, thereby causing a malfunction.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional disadvantages. As shown in FIG. 1, a phase excitation designation signal for designating an excitation mode of a stepping motor is provided.
A CPU for generating a rotation start designation pulse for instructing a start point of the rotation drive of the stepping motor, and a plurality of clock pulses, wherein the first rise of the clock pulse is synchronized with the rise of the rotation start designation pulse; The stepping motor generates a rotation designation clock having a different clock frequency according to the phase excitation designation signal, and based on the rotation designation clock, controls the stepping motor so that rising edges of the plurality of clock pulses are synchronized with microsteps of the stepping motor. A driving circuit for a stepping motor, comprising: a driver for generating a rotating phase current and supplying the phase current to the stepping motor;

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A drive circuit for a stepping motor according to an embodiment of the present invention will be described below with reference to the drawings. This circuit, as shown in FIG.
1 is a circuit comprising a driver 12 and driving a stepping motor M of two-phase excitation.

The CPU 11 generates a control signal S for instructing a driving state such as the rotation speed of the stepping motor M and an excitation mode.
The control circuit controls the drive circuit based on S11.
2, M3, and a rotation start designation pulse Po described later and output to the driver 12. Driver 12
Has a clock generator 13 and a phase current generator 14, and a phase for driving the stepping motor M based on the above-described mode designation signals M1, M2, M3 and a later-described rotation start designation pulse Po. This is a circuit that generates a current Io and supplies it to the stepping motor M. The mode designation signals M1, M2, and M3 are either low-level (hereinafter, referred to as "L") or high-level (hereinafter, referred to as "H") signals, and are 3-bit information in M1 to M3. Therefore, eight kinds of excitation modes can be designated by these combinations. For example, when M1, M2, and M3 are respectively selected as "0", "0", and "0", two phases are selected.
When "1", "0", or "0" is selected, it can be assigned as 1-2 phase.

The clock generator 13 is a circuit that generates a rotation designation clock CK11 based on the mode designation signals M1, M2, M3 and the rotation designation pulse Po, and supplies the rotation designation clock CK11 to the phase current generator 14. Among these, the rotation designation clock CK11 is a clock for rotating the motor by a predetermined angle in synchronization with the rise thereof, and the rotation start designation pulse is a clock for starting generation of the first pulse of the rotation designation clock. It is a pulse.

The phase current generating section 14 generates a rotation designation clock C
This is a circuit that generates a phase current Io based on K11, supplies it to the stepping motor M, and rotates it. Hereinafter, the operation of the above circuit will be described. According to the above circuit, first, the control signal SS11 for instructing the driving state such as the rotation speed of the stepping motor M and the excitation mode is input to the CPU.

Thus, two-phase, 1-2-phase, W1-2
The CPU 1 stores information as to whether any one of the excitation modes of the two-phase excitation and the 2W1-2-phase excitation is selected, information about the time of starting rotation, and how many times the stepping motor M is rotated.
1 is recognized. Next, mode designation signals M1, M2, M3 for instructing the excitation mode are generated in the CPU 1 and output to the driver 12. In the present embodiment, as an example, M
It is assumed that 1, M2, and M3 are "1", "1", and "0", respectively, and the excitation mode is 2W1-2 phase.

At the same time, a start-of-rotation designating pulse Po for determining the start of rotation of the stepping motor M is supplied to the CPU 11.
And output to the driver 12. The mode designation signals M1, M2, M3 and the rotation start designation pulse Po are input to a clock generator 13 in the driver 12, and the clock generator 13 generates a rotation designation clock CK11 and outputs it to the phase current generator 14. You. The rotation designation clock CK11 is generated so that the first clock rises in synchronization with the rise of the rotation start designation pulse Po as shown in FIG.

Thereafter, the phase current generator 14 generates a phase current Io related to the rotation of the stepping motor M based on the rotation specifying clock CK11, and generates the rotation specifying clock CK1.
The phase current Io that matches the rotation state specified by 1 is supplied to the stepping motor M, whereby the stepping motor M rotates by a predetermined angle. The actual rotation state will be described with reference to FIG. Here, the case where the rotation is performed from the origin O1 to O2 in FIG. 5 will be described.

In the above embodiment, driving in 2W1-2 phase is designated by mode designation signals M1, M2, M3 of "1", "1", and "0", respectively. 2W
As shown in FIG. 5, there are eight steps in which the motor ticks while rotating from O1 to O2 in the 1-2 phase.
The above-described rotation designation clock CK1 corresponds to the step.

That is, the first rotation designation clock CK1
The operation of ticking the first step shown in FIG. 5 in synchronism with the rising edge of the clock CK1 and ticking the second step in synchronism with the rising edge of the next clock CK1 is sequentially repeated. Reaches the origin O2 when the clock CK1 rises, and temporarily stops. In FIG. 5, the angle from the origin O1 to the origin O2 is 90 °,
One rotation (360 ° rotation) in FIG. 5 as described in the conventional example
Corresponds to 7.2 ° of the actual rotation angle of the stepping motor, and the angle 90 ° from the origin to the origin is １ ／ of 7.2 °.
1.8 degrees, that is, the basic step angle θs.

Usually, the motor moves from the origin to the origin and stops at the origin. During this operation, the actual rotation angle of the motor is the basic step angle θs (= 1.8 °).
Becomes At this time, if the excitation mode is predetermined,
When the motor moves from the origin to the next origin, that is, when the motor rotates by the basic step angle θs, the number of steps to be carved is predetermined. As described above, there are eight steps in the 2W1-2 phase. Also, as shown in FIG. 5, it can be seen in advance that 16 steps are required for 4W1-2 phase, 4 steps for W1-2 phase, 2 steps for 1-2 phase, and 1 step for 2 phase.

Therefore, if the excitation mode is determined, for example, in the 2W-12 phase, when moving from the origin to the origin, eight steps are engraved, and it is known in advance that eight rotation designation clocks CK11 are required. It is understood that the rotation state of the motor can be uniquely determined if the start time of the rotation is known. Therefore, in the present invention, the rotation specifying clock CK11 is not generated by the CPU 11, but only the rotation start specifying pulse Po for defining the first rotation start time and the mode specifying signals M1, M2, M3 are generated and the driver 12 is controlled.
And outputs the rotation designation clock CK by the clock generator 13 in the driver 12 based on the information.
11 is generated.

For this reason, the CPU 11 does not need to generate the rotation designation clock CK11 by itself as in the related art, so that when the high-speed rotation designation clock CK11 becomes necessary, for example, during 4W1-2-phase driving. The CPU does not need to generate such a high-speed rotation designation clock CK11 by the CPU itself. By generating such a high-speed clock, the burden on the CPU can be prevented from becoming excessive.

As a result, interrupt processing of other jobs is practically impossible, and the CPU operates almost exclusively for clock generation. In severe cases, the processing of other jobs is delayed and the stepping motor is delayed. It is possible to suppress a malfunction such as a shift in the rotational position of the camera. In this embodiment, a circuit for driving a two-phase stepping motor is described. However, the present invention is not limited to this. For example, the present invention may be applied to a driving circuit for a three-phase, five-phase stepping motor, or the like. A similar effect is achieved.

[0026]

As described above, according to the driving circuit for a stepping motor according to the present invention, the CPU does not generate a rotation designation clock for rotating the stepping motor in synchronization with its rise, but the driver generates the clock. The CPU merely generates a rotation start time designation pulse for designating the start time of the rotation designation clock and outputs the pulse to the driver. The conventional problem that the load on the CPU becomes excessive, interrupt processing of other jobs is practically impossible, and the inconvenience that the CPU operates almost exclusively for clock generation, In the worst case, the processing of other jobs was delayed and the rotation position of the stepping motor was shifted, sometimes causing a malfunction. It becomes possible to suppress the problem had come to occur.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a drive circuit of a stepping motor according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining an operation of a driving circuit of the stepping motor according to the embodiment of the present invention.

FIG. 3 is a circuit diagram of a driving circuit of a stepping motor according to a conventional example.

FIG. 4 is a timing chart illustrating an operation of a driving circuit of a stepping motor according to a conventional example.

FIG. 5 is a diagram illustrating an operation state of a drive circuit of a general stepping motor.

FIG. 6 is a diagram showing the relationship between the excitation mode of a general stepping motor and the number of rotation designation clocks.

[Explanation of symbols]

 11 CPU 12 Driver 13 Clock Generator 14 Phase Current Generator M Stepping Motor M1, M2, M3 Mode Setting Signal CK11 Rotation Designation Clock Io Phase Current Po Rotation Start Designation Pulse SS11 Control Signal

Claims (2)

[Claims] 1. A phase excitation designation signal for designating an excitation mode of a stepping motor, a CPU for generating a rotation start time designation pulse for instructing a start time of rotation drive of the stepping motor, and a plurality of clock pulses; The rise of the first clock pulse is synchronized with the rise of the start designation pulse, generates a rotation designation clock having a different clock frequency according to the phase excitation designation signal, and, based on the rotation designation clock, the plurality of clock pulses. And a driver for generating a phase current for rotating the stepping motor so as to synchronize the rising of the stepping motor with the microsteps of the stepping motor and supplying the phase current to the stepping motor. 2. A clock generator for generating the rotation specifying clock based on the rotation specifying clock and the phase excitation specifying signal, the driver generating the phase current based on the rotation specifying clock,
2. A driving circuit for a stepping motor according to claim 1, further comprising a phase current generating section for supplying the phase current to the stepping motor.