JPH07274592A - Drive circuit for stepping motor - Google Patents

Abstract

PURPOSE:To achieve highly accurate, highly reliable drive by generating phase signals indicating in which phase a stepping motor is positioned, feeding them back to a central processing unit, and thereby detecting the actual state of the stepping motor. CONSTITUTION:CPU 11 outputs excitation mode signals M1, M2, one of control command signals, number-of-revolutions specifying clock CLK, a rotational direction setting signal CWB and a reset signal RESET. Drive control signals A, B, AB, BB are generated in the phase signal generating section 17 in a driver 12 according to these signals and clock, and outputted to a stepping motor SM. At the same time a phase signal MO indicating the state of the stepping motor SM is generated in the driver 12, and is fed back to CPU 11. This makes it possible to drive and control the stepping motor SM in correspondence with its actual state, and enables drive with accuracy and reliability.

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 specifically, it is a microstep of a stepping motor used in applications such as a carriage section, an image reading section, a rotating drum section of a printer or a copying machine. The purpose is to improve the driving circuit.

[0002]

2. Description of the Related Art Before describing a conventional stepping motor, microstep driving of the stepping motor will be described with reference to FIG. FIG. 7 is a phase transition state diagram for explaining each excitation mode of micro-step driving when driving a two-phase stepping motor.

In the two-phase excitation mode, which is the mode shown on the innermost side of the concentric circles in FIG.
In the 1-2 phase excitation mode, which is a mode in which the motor rotates by 60 °, the motor rotates by 360 ° in eight steps, which is twice that. Further, the W1-2 phase excitation mode on the outer side is a mode in which the motor rotates 360 ° in 16 steps that is double that. In the 2W1-2 phase excitation mode, the motor rotates 360 ° in 32 steps that is double that. Mode.

That is, as described above, as the outer excitation mode in the concentric circles in FIG. 7 is set, the number of steps during rotation increases, and it is possible to drive at a low speed but with smooth and little vibration. As it goes to the inner excitation mode, the number of steps during rotation decreases, and although there is some vibration, high-speed drive can be performed, so the excitation mode is switched as necessary and the excitation mode suitable for the purpose is selected. Was.

Particularly, the operation of the carriage portion of the printer, the image reading portion of the copying machine, the rotating drum portion, etc., which requires high resolution by using the stepping motor, uses the microstep drive, and the vibration from the motor is small. It was driven by the method. For example, in the operation of the carriage unit, the image reading unit, the rotating drum unit, etc., microstep drive such as 2W1-2 phase excitation is used during acceleration,
Full-step driving such as two-phase excitation was used during constant speed driving, and micro-step driving was used during deceleration.

A drive circuit of a stepping motor for performing microstep driving of a stepping motor according to a conventional example will be described below with reference to FIG. The drive circuit of the stepping motor according to the conventional example is a CPU
It is a circuit that includes (1) and a driver circuit (2) and drives a stepping motor (3). According to this circuit, the driver (2) drives the microstepping of the stepping motor (3) based on the control pulse (SS) from the CPU (1).

[0007]

However, according to the conventional driving circuit as shown in FIG. 8, the CPU (1)
There was a case where the normal drive in accordance with the control signal (SS) from PC was not performed. That is, conventionally, a CPU is generally used.
A circuit for detecting the state of the control pulse (SS) is provided inside (1), and the state of the control pulse (SS) output to the driver (2), for example, counting the number of control pulses (SS). Is detected inside the CPU (1) to detect the actual position state of the stepping motor (3).

However, even if the control pulse (SS) is normally output, the drive signal from the driver (2) is normal due to some reason such as noise being added to the control pulse (SS) and input to the driver (2). When the output of the stepping motor (3) is stopped and the drive is not driven to the normal position, the current situation is that it cannot be dealt with at all.

[0009]

The present invention has been made in view of the above-mentioned conventional drawbacks, and as shown in FIG. 1, a central processing unit for outputting a control command signal (SS) of a stepping motor (SM). Section (11) and the control command signal (S
Based on S), the stepping motor (SM) is driven, and a phase signal (MO) indicating a position state indicating which phase the stepping motor (SM) is in is generated to generate the central processing unit (11). And a drive control unit (12) for feeding back to the stepping motor, the actual state of the stepping motor is detected, and a stepping motor drive circuit capable of driving the stepping motor with higher accuracy and reliability is provided. To do.

[0010]

[Operation] According to the stepping motor drive circuit of the present invention, as shown in FIG. 1, the central processing unit (11)
And a drive control section (12). That is, the central processing unit (11) causes the stepping motor (S
The control command signal (SS) of M) is output, and the stepping motor (SM) is driven based on this, and at the same time, the phase (MO) that indicates the position state of the stepping motor (SM) is driven. It is generated by the control unit (12) and fed back to the central processing unit (11).

For this reason, unlike the conventional drive circuit which is supposed to detect the actual position state of the stepping motor by counting the control pulses output from the CPU, which phase the stepping motor (SM) is Since the actual position state of whether the vehicle is in the air is fed back from the drive control unit (12) to the central processing unit (11), drive control can be performed accordingly, and the actual operating state of the motor can be met. It becomes possible to perform microstep driving with high accuracy and high reliability.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A stepping motor drive circuit according to an embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 2, the drive circuit of the stepping motor according to the embodiment of the present invention is a circuit including a CPU (11) and a driver (12) and includes coils (L1 to L).
4), which is a circuit for performing micro-step driving of a two-phase stepping motor (SM) used in a carriage section of a printer or a copying machine.

The CPU (11) is an example of a central processing unit, and is an excitation mode signal (M1, M) which is an example of a control command signal (SS) of a stepping motor (SM).
2), a rotation number designating clock (CLK), a rotation direction setting signal (CWB), an IC internal reset signal (RESET), and an origin restart signal (RETURN) are generated and output to the driver (12).

The driver (12) is an example of a drive controller and is a first stepping motor (SM).
-A phase signal (MO) indicating the position state of the stepping motor (SM) by supplying / non-supplying current to the fourth coil (L1 to L4) to drive the stepping motor (SM)
1, MO2) and outputs it to the CPU (11).

As shown in FIG. 2, the structure is such that the start-up detection circuit (14), the signal generation section (12B) and the drive section (1).
2C). The start-up detection circuit (14) is an example of the noise removal unit (12A), and is composed of four-stage flip-flop circuits, and when the origin restart signal (RETURN) and the motor rotation number designation (CLK) are started up, It is a circuit that cancels the noise of the original signal by delaying and outputting the signal up to "0011".

The signal generator (12B) comprises an up / down counter (15) and a phase signal generator (17).
Based on the rotation speed designation clock (CLK), the phase signal (M
O1, MO2) and drive control signals (A, B, AB, BB), which are an example of drive signals (DS), are generated. The up / down counter (15) is a circuit that outputs a count signal (KS) that counts the number of pulses of the rotation speed designation clock (CLK) to the reference signal generation circuit (18) and the phase signal generation unit (17).

The phase signal generator (17) supplies power MOSFETs (F1 to F) based on the divided reference clock (CK), PWM signal (PS) and count signal (KS).
4) Drive control signals (A, B, AB, BB) which are examples of drive signals (DS) and phase signals (MO1, MO2)
Is a circuit for generating and outputting. The drive unit (12C)
Based on the drive control signals (A, B, AB, BB), the coils (L1 to L) forming the stepping motor (SM)
A stepping motor (SM) is micro-step-driven by supplying / not supplying a current to 4), and a PWM circuit (16) and a reference signal generation circuit (18)
And D / A converters (19A, 19B), comparators (20A, 20B), and power MOSFETs (F1 to F1).
F4), the clock generation circuit (21), and the frequency division circuit (2
2) and mode setting (13).

The PWM circuit (16) includes a comparator (2
0A, 20B) PWM signal (P
S) is output to the phase signal generator (17). The reference signal generation circuit (18) is a circuit that outputs a 10-bit reference signal (ST) to each of the D / A converters (19A, 19B) based on the count signal (KS).

The D / A converter (19A, 19B) is
Digital / analog conversion of reference signal (ST) (hereinafter D
/ A conversion) to generate stepwise pseudo sine waves (DAOUT, DBOUT) corresponding to the A phase and the B phase, respectively, and generate the comparator (20) via the operational amplifiers (OP1, OP2).
A, 20B). Comparator (2
0A, 20B) is a step-like pseudo sine wave (DAOUT, DBOUT) input through the operational amplifier (OP1, OP2).
And a voltage obtained by converting the drain current of the driving power MOSFETs (F3, F4) into a voltage, and outputting the comparison result to the PWM circuit (16).

The power MOSFETs (F1 to F4) include coils (L1 to L1) which form a stepping motor (SM).
L4) is a switching element for driving which supplies / non-supplies current to each. The clock generation circuit (21) generates a reference clock (CK) for the entire driver (12),
This is a circuit for outputting to the frequency dividing circuit (22).

The frequency dividing circuit (22) is a reference clock (CK).
Is a circuit that divides the frequency and outputs it to the D / A converters (19A, 19B) and the phase signal generation unit (17). The mode setting circuit (13) is a circuit that selects the excitation mode of the stepping motor (SM) based on the excitation mode signals (M1, M2) and outputs it to the up / down counter (15).

The operation of the drive circuit for the stepping motor according to this embodiment will be described below. First,
Initial settings for the entire system are made. At this time, a reset signal (RESET) inside the IC resets all the circuits in the circuit to the initial state. Next, the excitation mode is set to 2 by the 2-bit excitation mode signal (M1, M2).
Phase, 1-2 phase, W1-2 phase, or 2W1-2 phase is set, and the rotation direction setting input (CW
B) is input from the CPU (11) to the driver (12) to determine the rotation direction.

Next, the rotation speed designation clock (CLK) is input and input to the start-up detection circuit (14), where the noise on the rotation speed designation clock (CLK) is removed and the up / down counter (15). ) Is entered. At the same time, the rotation direction setting signal (CWB) and the excitation mode signal (M1,
And M2) are input to the up / down counter (15).

Next, the rise detection circuit (14) removes noise when the rotation number designation clock (CLK) rises. That is, the rotation speed designation clock (CLK)
Is delayed by the four-stage flip-flops forming the rise detection circuit (14) and is not output from the rise detection circuit (14) until the number of clocks exceeds "0011" from the beginning.

Actually, the noise generated at the time of startup is generated in the range where the clock number is less than "0011" from the beginning,
Since it is unlikely that noise will be generated over a larger time zone than this, this delay removes noise of the rotation speed designation clock (CLK). Next, the rotation speed designation clock (CL) from which noise has been removed by the startup detection circuit (14) as described above.
K) is counted by the up / down counter (15) in synchronization with the reference clock (CK) from the clock generation circuit (21), and the count result is stored in the reference signal generation circuit (18) and the phase signal generation unit (17). Is output.

Next, the output signal of the up / down counter (15) is counted by the reference signal generation circuit (18) composed of a counter, and the 10-bit reference which is the basis for generating the stepwise pseudo sine wave later. The signal (ST) is input to the D / A converters (19A, 19B). Next, the reference signal (ST) of the reference signal generation circuit (18) is D / A converted by the D / A converters (19A, 19B) to generate a stepped pseudo sine wave (DAOUT, DBOUT).

This pseudo sine wave (DAOUT, DBOUT) is D / A
Impedance matching is performed by operational amplifiers (OP1, OP2) connected to the converters (19A, 19B),
It is output to the inverting input unit (-) of the comparator (20A, 20B). The non-inverting input section (+) of the comparators (20A, 20B) is connected to the drains of the power MOSFETs (F3, F4) that drive the stepping motor (SM), and these drain currents and the operational amplifier (O
The output signal from P1, OP2) is compared with the comparator (20
A, 20B) and the comparator (2
0A, 20B) output pulse rising edge is PW
It is input to the M circuit (16), and the PWM circuit (16) outputs P
The WM-modulated output signals of the comparators (20A, 20B) are output to the phase signal generator (17).

Thereafter, the phase signal generator (17) synchronizes with the reference clock (CK) from the clock generator (21) based on the count signal (KS) output from the up / down counter (15), Power MOSFET (F for driving stepping motor (SM)
The signals (A, B, AB, BB) for driving (1 to F4) are output to the power MOSFETs (F1 to F4), so that the motor starts driving according to the instruction of the CPU.

Further, the phase signal generator (17) allows the motor to actually determine which phase (A, B,
A 2-bit phase signal (MO1, MO2), which is a signal indicating whether it is in AB, BB), is generated and input to the CPU (11). For example, the phase signals (MO1, MO2) are

[0030]

[Table 1]

By setting as follows, MO1
When "1" is and MO2 is "0", the stepping motor (SM) is in the A phase and the CPU (1
1) The stepping motor (SM) is the phase A, B of FIG.
Phase signal (MO phase, AB phase, BB phase)
1, MO2). As a result, if the stepping motor (SM) is not operating normally and is not in the phase it should be,
It becomes possible for the CPU (11) to control the stepping motor (SM) to return it to the normal position.

Below, the actual driving condition of the motor by the above-mentioned circuit operation is shown in the timing chart of FIG.
This will be described with reference to the phase state transition diagram of FIG. The mode shown in FIG. 3 is a 2W1-2 phase excitation mode, and M1
= M2 = 1. In synchronization with the rising edge of the reset signal (RESET), the phase signal generator (17) generates the drive control signals (A, B, AB, BB) and the 2-bit phase signals (MO1, MO2). At this time, since the rotation direction setting input (CWB) is at a low level (hereinafter referred to as "0"), this motor rotates counterclockwise during this period according to FIG.

First, since the drive control signals (A, BB) are at a high level (hereinafter referred to as "1") and the drive control signals (AB, B) are "0", the MOSFET (F
1, F4) is turned on, and a current flows through the coils (L1, L4). At this time, the phase signal (MO1) and the phase signal (MO
Since both 2) are "1", it can be seen from Table 1 that the motor is currently in the BB phase, and the CPU (1
1) can also recognize it.

Next, since the drive control signals (A, B) are "1" and the drive control signals (AB, BB) are "0", the MOSFETs (F1, F2) are turned on and the coils are turned on. A current flows through (L1, L2). At this time, the phase signal (M
Since O1) is "1" and the phase signal (MO2) is "0", it can be seen from Table 1 that the motor is currently in phase A, and the CPU (11) can also recognize it. .

Next, since the drive control signals (AB, B) are "1" and the drive control signals (A, BB) are "0", the MOSFETs (F2, F3) are turned on,
A current flows through the coils (L2, L3). At this time, since the phase signal (MO1) is "0" and the phase signal (MO2) is "1", it can be seen from Table 1 that the motor is currently in the B phase, and the CPU (11) also Can be recognized.

Next, since the drive control signals (AB, BB) are "1" and the drive control signals (A, B) are "0", the MOSFETs (F3, F4) are turned on and the coils are turned on. A current flows through (L3, L4). At this time, since the phase signals (MO1) are both “0”, it can be seen from Table 1 that the motor is currently in the AB phase.
(11) can also recognize it.

As described above, which phase the motor is currently in is determined by the phase signals (MO1, MO2) from the CPU (1
Since 1) can recognize, even if the motor is in a position different from the actual position of the motor, the CPU (11) outputs a command to correct it and drives the motor correctly. It becomes possible to control.

The W1-2 phase excitation mode shown in FIG. 4, the 1-2 phase excitation mode shown in FIG. 5, and the two shown in FIG.
The operation in the phase excitation mode is basically 2W in FIG.
Since it is the same as the 1-2 phase excitation mode, description thereof will be omitted.
As described above, according to the driving circuit of the stepping motor in the embodiment of the present invention, as shown in FIG.
It comprises a U (11) and a driver (12).

That is, the excitation mode signals (M1, M2) which are examples of the control command signal (SS) of the stepping motor (SM) by the CPU (11), the rotation speed designation clock (CLK), and the rotation direction setting signal (CWB). And a reset signal (RESET) are output, and based on these signals, drive control signals (A,
B, AB, BB) are generated by the phase signal generation unit (17) in the driver (12) and output to the stepping motor (SM), and at the same time, the phase (MO) indicating the state of the stepping motor (SM) is output to the driver (MO). 12) CP generated
Returned to U (11).

Therefore, unlike the conventional case in which the actual position state of the stepping motor is detected by counting the control pulses output from the CPU,
Since the phase signals (MO1, MO2) indicating the state of which the stepping motor (SM) is actually in are fed back from the driver (12) to the CPU (11),
The drive control can be performed accordingly, and it becomes possible to perform highly accurate and highly reliable micro step drive in accordance with the actual operating state of the motor.

In this embodiment, the micro-step driving of the two-phase stepping motor has been described, but the present invention is not limited to this, and for example, for a four-phase or eight-phase stepping motor, a 2-bit phase signal is currently used. This can be dealt with by setting (MO1, MO2) to 4 bits or 8 bits.

[0042]

As described above, the drive circuit for the stepping motor according to the present invention includes the central processing unit (11) and the drive control unit (12). Unlike the conventional method in which the actual position state of the stepping motor was detected by counting the control pulses that were being performed, drive control can be performed according to the actual state of the stepping motor (SM). High accuracy, which matches the actual operating state of the motor
It becomes possible to drive a highly reliable stepping motor. .

[Brief description of drawings]

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

FIG. 2 is a circuit diagram of a drive circuit for a stepping motor according to an embodiment of the present invention.

FIG. 3 is a first timing chart explaining the operation of the drive circuit of the stepping motor according to the embodiment of the invention.

FIG. 4 is a second timing chart illustrating the operation of the stepping motor drive circuit according to the embodiment of the invention.

FIG. 5 is a third timing chart explaining the operation of the stepping motor drive circuit according to the embodiment of the invention.

FIG. 6 is a fourth timing chart explaining the operation of the stepping motor drive circuit according to the embodiment of the invention.

FIG. 7 is a diagram illustrating an excitation mode and a phase state of microstep driving of a stepping motor.

FIG. 8 is a circuit diagram of a drive circuit of a stepping motor according to a conventional example.

[Explanation of symbols]

 (11) CPU (Central Processing Unit) (12) Driver (Drive Control Unit) (12A) Noise Removal Unit (12B) Signal Generation Unit (12C) Drive Unit (13) Mode Setting Unit (14) Start-up Detection Circuit ( 15) Up-down counter (16) PWM circuit (17) Phase signal generator (18) Reference signal generator (19A) D / A converter (19B) D / A converter (20A) Comparator (20B) Comparator (21) Clock Generating circuit (22) Dividing circuit (SM) Stepping motor (F1 to F4) Power MOSFET (L1 to L4) Coil (A, B, AB, BB) Drive control signal (DS) Drive signal (CK) Reference clock (KS) ) Count signal (PS) PWM signal (ST) Reference signal (DAOUT, DBOUT) Pseudo sine wave (M1, M2) Excitation Mode signal (CLK) Rotation speed designation clock (CWB) Rotation direction setting signal (RESET) Reset signal (RETURN) Origin restart signal (MO1, MO2) Phase signal

Claims (2)

[Claims] 1. A central processing unit (11) for outputting a control command signal (SS) of a stepping motor (SM), and driving the stepping motor (SM) based on the control command signal (SS), Further, the central processing unit (11) generates a phase signal (MO) indicating a position state indicating which phase the stepping motor (SM) is in.
A drive circuit for a stepping motor, comprising: 2. A central processing unit (11) for outputting a control command signal (SS) of a stepping motor (SM), and driving the stepping motor (SM) based on the control command signal (SS), Further, the central processing unit (11) generates a phase signal (MO) indicating a position state indicating which phase the stepping motor (SM) is in.
And a drive control unit (12) for returning the control command signal (SS) to the drive control unit (12).
A noise removing unit (12A) for removing the noise of the signal generator, and a signal generating unit (12A) for generating the drive signal (DS) and the phase signal (MO) based on the control command signal (SS) from which the noise is removed 12B) and a drive unit (12C) for driving the stepping motor (SM) based on the drive signal (DS), a stepping motor drive circuit.