JP3459530B2 - Stepping motor drive circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A conventional stepping motor drive circuit will be described below with reference to FIG. As shown in FIG. 3, this circuit is composed of a CPU 1 and a driver 2 and drives a two-phase excitation stepping motor M.

According to the above circuit, first, the control signal SS1 for instructing the driving state such as the rotation speed of the stepping motor and the excitation mode is input to the CPU. This allows two phases,
Information indicating whether any one of the 1-2 phase, W1-2 phase, and 2W1-2 phase excitation modes is selected, the time when the rotation starts, and the information about how many times the stepping motor M is rotated are stored in the CPU 1. Recognized in.

Then, mode designating signals M1, M2 and M3 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. Along with this, 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 its rising.

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

Based on the rotation designation clock CK1 and the mode designation signals M1, M2 and M3, the driver 2 generates a phase current Io for driving the stepping motor M,
By supplying to the stepping motor M, the stepping motor M rotates by a predetermined angle in synchronization with the rising of the rotation designation clock CK1 according to 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 of FIG. 5 (36
(0 ° rotation) is the actual rotation angle of the stepping motor.
Corresponds to 2 °. Normally, the stepping motor rotates in the steps of origin → origin shown in FIG. That is, considering, for example, 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 notching eight steps thereafter, and then again at the next origin O2. It rotates toward the origin O3. The eight steps to be engraved at this time are the rotation designation clock CK1 described above.
It will be engraved in sync with the rise of.

The origin and the origin that appears next (for example, O1 and O
The angle with 2) is 90 ° in FIG. 5, but since one rotation (360 ° rotation) in FIG. 5 corresponds to the actual rotation angle of 7.2 ° of the stepping motor as described above, this angle When converted into the actual rotation angle of the stepping motor, 1.
Corresponds to a rotation of 8 °. Since the actual motor repeats rotation / stop at each step, this 1.8 ° is referred to as a basic step angle θs.

FIG. 6 is a chart showing the number of rotation designating clocks CK1 required for actually rotating the stepping motor by 360 ° for each phase excitation mode. As shown in this chart, the basic step angle is 1.8 ° when driving a two-phase stepping motor, and 200 when driving two-phase.
400 pieces in 1-2 phase excitation, 800 pieces in W1-2 phase
1600 for 2W1-2 phase, 3 for 4W1-2 phase
As many as 200 clocks CK1 are required.

[0010]

However, the above-mentioned conventional drive circuit as shown in FIG. 5 has the following problems. The above rotation designation clock CK1 is
All are generated by the CPU 1 as software. The CPU 1 has an original function of controlling the drive circuit. However, when the stepping motor M is rotating, the CPU 1 mostly operates to generate the rotation designation clock CK1.
Will be overloaded.

That is, at the time of low speed rotation such as two phases,
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, the high-speed clock CK1 that requires as many as 3200 clocks is generated in one rotation as described above, so that in such a case, interrupt processing of other jobs is practically impossible, Almost inconveniently, the CPU operates only for clock generation, and in some cases, processing of other jobs may be delayed and the rotational position of the stepping motor may be misaligned.

[0012]

The present invention has been made in view of the above-mentioned drawbacks of the prior art. As shown in FIG. 1, a phase excitation designation signal for designating an excitation mode of a stepping motor,
The CPU includes a CPU that generates a rotation start time designation pulse that indicates the start time point of the rotation drive of the stepping motor, and a plurality of clock pulses. The rising edge of the first clock pulse is synchronized with the rising edge of the rotation start time designation pulse. A rotation designation clock having different clock frequencies is generated according to the phase excitation designation signal, and based on the rotation designation clock, the stepping motor is configured so that the rising edges of the plurality of clock pulses are synchronized with the microsteps engraved by the stepping motor. The above problem is solved by a drive circuit for a stepping motor, which has a driver that generates a rotating phase current and supplies it to the stepping motor.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION 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, a driver 12 is a circuit for driving a two-phase excitation stepping motor M.

The CPU 11 has a control signal S for instructing a driving state such as the number of rotations of the stepping motor M and an excitation mode.
It controls the drive circuit on the basis of S11 and, together with its function, mode designating signals M1 and M described later.
2, M3 and a rotation start designation pulse Po described later are generated 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 designating signals M1, M2, M3 and a rotation start designation pulse Po described later. It is a circuit that generates a current Io and supplies it to the stepping motor M. The mode designating signals M1, M2 and M3 are either low level (hereinafter referred to as “L”) or high level (hereinafter referred to as “H”) signals, and M1 to M3 form 3-bit information. Therefore, eight kinds of excitation modes can be designated by these combinations. For example, when M1, M2 and M3 are selected as "0", "0" and "0" respectively, two phases are selected,
When selecting "1", "0", or "0", it can be assigned as 1-2 phase.

The clock generator 13 is a circuit for generating the rotation designation clock CK11 based on the mode designation signals M1, M2, M3 and the rotation start designation pulse Po and supplying it to the phase current generator 14. Of these, the rotation designation clock CK11 is a clock for rotating the motor by a predetermined angle in synchronization with its rising, and the rotation start designation pulse is for starting the generation of the first pulse of the rotation designation clock. It is a pulse.

The phase current generator 14 uses the rotation designation clock C.
It is a circuit that generates a phase current Io based on K11 and supplies it to the stepping motor M to rotate it. The operation of the above circuit will be described below. 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.

As a result, two phases, 1-2 phase, W1-2
Information indicating which one of the two-phase and 2W1-2-phase excitation modes is selected, the time when the rotation starts, and the information about how many times the stepping motor M is rotated.
Recognized by 1. Next, in the CPU 1, mode designating signals M1, M2, M3 for instructing the excitation mode are generated and output to the driver 12. In the present embodiment, as an example, M
1, M2 and M3 are "1", "1", and "0", respectively, and the excitation mode is 2W1-2 phase.

At the same time, the rotation start designation pulse Po for determining the start time of the rotation of the stepping motor M is the CPU 11
And is output to the driver 12. The mode designating signals M1, M2, M3 and the rotation start designation pulse Po are input to the clock generator 13 in the driver 12, and the clock generator 13 generates the rotation designation clock CK11 and outputs it to the phase current generator 14. It 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 the phase current Io relating to the rotation of the stepping motor M based on the rotation designation clock CK11, and the rotation designation clock CK1.
The phase current Io that matches the rotation state designated by 1 is supplied to the stepping motor M, which causes the stepping motor M to rotate by a predetermined angle. The actual rotation state will be described with reference to FIG. Here, a case where the rotation is performed from the origin O1 to O2 in FIG. 5 will be described.

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

That is, the first rotation designation clock CK1
5, the first step shown in FIG. 5 is carved, and the second step is carved in synchronization with the next clock CK1 rising. When the clock CK1 of rises, it reaches the origin O2 and temporarily stops. In FIG. 5, the angle from the origin O1 to the origin O2 is 90 °,
As described in the conventional example, one rotation of FIG. 5 (360 ° rotation)
Corresponds to 7.2 ° of the actual rotation angle of the stepping motor, and the angle 90 ° from the origin to the origin is ¼ of 7.2 °.
Corresponding to the basic step angle θs.

The motor normally moves from the origin to the origin and temporarily stops at the origin, during which 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,
The number of steps to be carved when the motor moves from the origin to the next origin, that is, when the motor rotates by the basic step angle θs is predetermined. As described above, there are 8 steps in the 2W1-2 phase. Further, as shown in FIG. 5, it is known in advance that 16 steps are required in the 4W1-2 phase, 4 steps in the W1-2 phase, 2 steps in the 1-2 phase, and 1 step in the 2 phase.

Therefore, if the excitation mode is determined, for example, in the 2W-12 phase, it is known in advance that eight steps are engraved when moving from the origin to the origin, and eight rotation designation clocks CK11 are required. It is understood that the rotation state of the motor can be uniquely determined if the time when the rotation starts is known. Therefore, in the present invention, the rotation designation clock CK11 is not generated by the CPU 11, and only the rotation start designation pulse Po that defines the first rotation start time and the mode designation signals M1, M2, M3 are generated and the driver 12 is generated.
To the rotation designation clock CK by the clock generator 13 in the driver 12 based on these 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 conventional case. Therefore, for example, when the high speed rotation designation clock CK11 is required as in the case of driving the 4W1-2 phase. Does not need to generate such a high-speed rotation designation clock CK11 by the CPU itself, and by generating such a high-speed clock, it is possible to prevent the CPU from being overloaded.

As a result, the interrupt processing of other jobs is practically impossible and the CPU operates almost only for clock generation. In the worst case, the processing of other jobs is delayed and the stepping motor is delayed. It is possible to prevent malfunctions such as the rotational position of being misaligned. Although the present embodiment describes a circuit for driving a two-phase stepping motor, the present invention is not limited to this, and may be applied to a three-phase, five-phase stepping motor drive circuit, for example. Has the same effect.

[0026]

As described above, according to the drive circuit of the stepping motor of the present invention, the CPU does not generate the rotation designation clock for rotating the stepping motor in synchronization with its rising, but the driver generates it. However, since the CPU only generates the rotation start designation pulse that specifies the generation start time of the rotation designation clock and outputs it to the driver, it is different from the conventional method when generating the high speed rotation designation clock. A problem that has occurred in the past such that the burden on the CPU becomes excessive, interrupt processing of other jobs is virtually impossible, and the CPU operates almost only for clock generation, In a severe case, it could even cause a malfunction such that the rotation position of the stepping motor was misaligned due to the delay in processing other jobs. It becomes possible to suppress the problem had come to occur.

[Brief description of drawings]

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

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

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

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

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

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

[Explanation of symbols]

11 CPU 12 drivers 13 Clock generator 14-phase current generator M stepping motor M1, M2, M3 mode setting signal CK11 rotation specified clock Io phase current Po designated pulse at the start of rotation SS11 control signal

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Claims (2)

(57) [Claims] 1. A multi-bit instructing an excitation mode of a stepping motor based on a control signal instructing a rotation speed of the stepping motor and a driving state of the excitation mode.
And a driver having a clock generator and a phase current generator, which generates a rotation start time designation pulse for instructing the start time of the rotation drive of the stepping motor, and a driver generated by the CPU. When the mode designation signal and the rotation start designation pulse are input to the clock generator of the driver, the rising of the rotation start designation pulse is synchronized with the rising of the first rotation designation clock pulse generated from the clock generator. And generating a rotation designation clock having a different number of clocks according to the mode designation signal, and based on the rotation designation clock from the phase current generator.
The phase current to generate a stepping motor
Drive circuit for stepping motor, which is characterized by rotating only . 2. The stepping motor is from the origin to the origin.
Move and stop at the origin once, then the excitation mode
Generates from the clock generator from origin to origin
Predetermine the number of clocks for the specified rotation clock
Stepping motor driving circuit according to claim 1, characterized in that.