JP3212232B2 - Step-out detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step-out detecting device for detecting a change in a load applied to a stepping motor or the like and a step-out of a step.

[0002]

In general, the stepping motor 1 of 4-phase excitation drive, as shown in FIG. 14, a parallel circuit composed of the exciting transistor 2 and the diode 3 of NPN type for exciting the respective excitation phase 4 are connected to the respective excitation phases.

A drive control signal (drive pulse) VA as shown in FIG. 16A is supplied from a CPU (central processing unit) 11 shown in FIG. 15 via a motor drive circuit 14 to the base of the exciting transistor 2. Is supplied to excite the respective excitation phases to drive the stepping motor 1.

[0004] Then, out detection <br/> equipment of the stepping motor 1, the emitter grounded in excitation magnetizing transistor 2 via the resistor 7, disengagement of the connection point between the exciting transistor 2 and the resistor 7 The step-out detection voltage VRS is monitored.
The motor was determined to lose synchronism based on RS.

In FIG. 15, reference numeral 12 denotes an R which stores program data and the like for the CPU 11 to perform step-out detection control.
OM (read only memory), 13 is I / O port
It is. The CPU 11, the ROM 12, the I / O port 13, and the motor drive circuit 14 are electrically connected by a bus line 15.

The motor drive circuit 14 has a D / A conversion circuit.
With a road (not shown) from the CPU 1116
Digital signal (drive control signal VA) as shown in FIG.
Is converted to an analog signal, and a step
To the base of transistor 2 of each excitation phase of
A motion signal is supplied.

An output terminal of a comparator 16 is connected to the I / O port 13, and this output terminal is connected to the I / O port 13.
The connection point with the port 13 is connected to the power supply terminal Vcc via the resistor 17.
(5V).

The comparator 16 has an inverting terminal (-) connected to a reference voltage power supply 18, and a non-inverting terminal (+) connected to a connection point between the exciting transistor 2 and the resistor 7. This comparator 16 has a step-out detection voltage VRS.
Is compared with a reference voltage, and the output changes according to the comparison result. The output is output to the I / O port 13.

Specifically, when the step-out detection voltage VRS is lower than the reference voltage, the port output P from the I / O port 13
0, and when the step-out detection voltage VRS is higher than the reference voltage,
The port output P from the I / O port 13 becomes P = 1.

In such a step-out detecting device, when a drive control signal is supplied from the CPU 11 and the stepping motor 1 is driven, the driving current during normal driving, that is, when the stepping motor 1 is not out of step or the like, is supplied with a drive current. (IA), as shown in FIG. 16 (b), rises from when the driving control signal is turned from oFF to oN from CPU 11,
It reaches the peak (1A) at timing A when the drive control signal from the CPU 11 changes from on to off. Then descend slowly.

The out-of-step detection voltage (VRS) also has a waveform similar to the drive current (IA) as shown in FIG. 2C. The peak voltage VRS at the timing A is such that the resistance value of the resistor 7 is 1Ω. Then, 1A × 1Ω = 1V.

[0012] However, if the step-out or the like to the stepping motor 1 occurs, the drive current (IA), as shown in FIG. 16 (d), the rise becomes steeper at the timing A in comparison with the normal driving operation, the peak current Is 1.2 A, which is larger than that during normal driving. According to the drive current (IA), the step-out detection voltage (VRS) also rises sharply as compared with the normal drive, as shown in FIG.
2A × 1Ω = 1.2 V, which is larger than that during normal driving.

Utilizing such a difference between the waveforms of the drive current IA at the peak (timing A) between the normal drive and the step-out of the stepping motor 1, the drive current I
A step-out detection voltage VRS that changes according to A is detected via the comparator 16 and the I / O port 13 after a predetermined time has elapsed from the timing A, and the step-out motor 1 is judged to be out of step based on the detection result.

That is, specifically, the I / O port 13
If the port output P from the
It is determined that the stepping motor 1 is out of step if the port output P from the I / O port 13 is 1.

[0015]

However, in such a stepping motor, the difference between the peak current (1A) during normal driving and the peak current (1.2A) during step-out is generally about 0.2A. Therefore, if the resistance value of the resistor 7 is 1Ω, the difference in the step-out detection voltage VRS becomes a very small voltage of about 0.2 V. Therefore, it is difficult to accurately determine whether the motor 1 has stepped out.

It is conceivable to increase the out-of-step detection voltage VRS by increasing the resistance value of the resistor 7. However, in such a case, power consumption due to generation of Joule heat of the resistor 7 or the like is considered. Becomes large, and accordingly, the power consumption of the whole circuit becomes large.

Accordingly, an object of the present invention is to provide a step-out detecting device capable of reliably detecting step-out.

[0018]

According to a first aspect of the present invention, there is provided a stepping motor driven by exciting a plurality of exciting phases by an on / off operation of an exciting transistor, and a back electromotive force generated in the exciting phase. Waveform into a pulse waveform
A back electromotive force detection circuit formed by connecting a series circuit of a pair of constant voltage diodes having their cathodes connected to each other and a resistance voltage dividing circuit to a power supply terminal; and an anode at a connection point between the excitation phase of the stepping motor and the excitation transistor. And a backflow prevention diode whose cathode is connected to the cathode connection point of each constant voltage diode of the back electromotive voltage detection circuit, and a pulse waveform generated at the voltage dividing point of the resistance voltage division circuit of the back electromotive voltage detection circuit
The step-out detection voltage is monitored and the time width of this step-out detection voltage is monitored.
Is longer than the time width during the normal driving of the stepping motor.
A step-out detection determining means for determining that the stepping motor has stepped out when the stepping motor is short .

[0019]

According to a second aspect of the present invention, the anodes of the backflow prevention diodes are separately connected to all the connection points of the excitation phase and the excitation transistor, and the cathodes of all the backflow prevention diodes are connected. The common terminal is connected to the cathode of each constant voltage diode of the back electromotive voltage detection circuit, and the head of the waveform of the back electromotive voltage generated in each excitation phase of the stepping motor at the time of energizing driving of the stepping motor is set to a predetermined constant voltage value. time limit is out detection device according to claim 1, wherein setting the Zener voltage of the constant voltage diode to be continuous.

According to a third aspect of the present invention, there is provided a stepping motor driven by exciting a plurality of exciting phases by turning on and off an exciting transistor, a pair of constant voltage diodes having cathodes connected to each other, and a resistive voltage divider. A back electromotive voltage detection circuit in which a series circuit with the circuit is connected to a power supply terminal, an anode is connected to a connection point between an exciting phase and an exciting transistor, and a cathode of each constant voltage diode of the back electromotive voltage detection circuit. The backflow prevention diode to which the cathode is connected, the step-out detection voltage generated at the voltage dividing point of the resistance voltage divider circuit of the back electromotive voltage detection circuit is compared with a preset reference voltage, and the step-out detection voltage is higher than the reference voltage. A comparison circuit that detects a time when the detection circuit is turned on, and a detection time storage unit that stores a detection time from the comparison circuit when the stepping motor is energized.
When the stepping motor is driven, the detection time from the comparison circuit is monitored, and the detection time from the comparison circuit is compared with the detection time during normal driving extracted from the detection time storage means, and the detection time from the detection circuit is determined. Is provided with step-out determining means for determining that the stepping motor has stepped out when the detection time is shorter than the detection time at the time of normal driving.

[0022]

The principle of the present invention as described in claim 1 having such a configuration will be described.

[0023]

[0024]

[0025]

[0026]

The step-out detection voltage in the present invention rises when the excitation transistor is turned off from on based on the back electromotive force generated in each excitation phase of the stepping motor,
The peak voltage is limited by one of the constant voltage diodes (a constant voltage diode whose anode is connected to the power supply terminal) to a predetermined voltage, and thereafter, the other constant voltage diode (the cathode has one constant voltage diode). Drops rapidly based on the zener voltage of a constant voltage diode connected to the power supply. The step-out detection voltage in this case has a substantially pulse waveform.

The step-out detection voltage, when loss of synchronism of the stepping motor, than in the normal driving peak of the counter electromotive force becomes large resulting in the excitation phase, because then suddenly becomes small, and the time limit for loss of synchronism detection voltage It is shorter than during normal driving. Therefore, out detection voltage after the time limit elapses, the substantially pulse waveform lower descending it is rather fast during out-. Therefore, this
By detecting the voltage after the lapse of the time limit, it is possible to determine whether or not the stepping motor is out of synchronization.

In the present invention, by utilizing such a principle, the step-out detection voltage is monitored by the step-out detection judging means, and the step-out detection of the stepping motor is determined based on the step-out detection voltage. .

Next, to explain the principles of the present invention of claim 2 wherein.

By setting the zener voltage of each constant voltage diode so that the time limit of one constant voltage diode (constant voltage diode whose anode is connected to the power supply terminal) of the step-out detection voltage in each excitation phase continues. The step-out detection voltage at the time of normal driving of the stepping motor becomes a substantially constant voltage.

On the other hand, when the stepping motor is out of synchronization, the time limit is shorter than that in the normal driving, so that the out-of-step detection voltage has a substantially pulse waveform. Therefore, by detecting the pulse waveform of the step-out detection voltage, it can be determined whether or not the stepping motor has stepped out.

In the present invention, utilizing such a principle, the step-out detection voltage is monitored by the step-out detection judging means, and the step-out motor is judged to be out of step based on the step-out detection voltage. .

Next, the principle of the present invention described in claim 3 is the same as the principle of the present invention described in claim 1 described above.

In the present invention, by utilizing this principle, the limit time (detection time) of the step-out detection voltage during normal driving of the stepping motor is detected in advance by the comparison circuit and stored in the detection time storage means. Then, when the stepping motor to monitor the time limit from the comparison circuit (detection time), the time limit from the comparator circuit (detection time), the normal driving taken out from the detection time storage means the time limit (detection time)
When the time limit (detection time) from the comparison circuit is shorter than the time limit (detection time) during normal driving, it is determined that the stepping motor has stepped out.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an out-of-step detecting apparatus for an electronic device having a unipolar stepping motor will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of this embodiment.
Reference numeral 21 denotes a four-phase excitation unipolar stepping motor. Each excitation phase (A phase, B phase) of this stepping motor 21
Phase, C phase and D phase), one terminal of which is a common terminal, and this common terminal is connected to a motor drive power supply Vc (for example, 26 V).

The other terminal of each excitation phase of the stepping motor 21 is connected to a parallel circuit 24 composed of an NPN transistor 22 and a diode 23 for exciting each excitation phase.

Specifically, the collector of the transistor 22 of each parallel circuit 24 is connected to each excitation phase of the stepping motor 21, and the emitter of the transistor 22 is grounded. A diode 23 is connected between the collector and the emitter with the polarity shown.

The drive current IA of each excitation phase of the stepping motor 21 changes during normal driving, that is, when there is no step-out or the like of the stepping motor 21, as shown in FIG. When the load applied to the stepping motor 21 increases or the step loses synchronism, it changes as shown in FIG.

The anode of the backflow prevention diode 25 is connected to the connection point between the other terminal of each excitation phase of the stepping motor 21 and the transistor 22. The cathode of the backflow prevention diode 25 is connected to the back electromotive voltage. It is connected to the detection circuit 26.

More specifically, the back electromotive voltage detection circuit 26 is constituted by a series circuit of a constant voltage diode 27 and a resistor voltage dividing circuit having resistors 28 and 29 connected in series. Is connected to the power supply terminal Vcc. Further, the cathode of the constant voltage diode 27 is connected to the cathode of the backflow preventing diode 25.

The cathode voltage VR of the constant voltage diode 27 changes as shown in FIG. 3C during normal driving, and changes as shown in FIG.

The configuration of the control unit in the present embodiment, FIG. 15
However, in the present embodiment, the non-inverting terminal (+) of the comparator 16 is connected to the voltage dividing point of the resistors 28 and 29 of the back electromotive voltage detection circuit 26. I have.

In the present embodiment, the CPU 11 is provided with a counter for counting the time for setting the output timing of the motor drive pulse and a counter for counting the time for setting the timing for detecting the step-out.

The CPU 11 performs step-out detection control as shown in FIG. That is, C
The PU 11 firstly receives a drive control signal (drive pulse) as shown in FIG. 3A via the motor drive circuit 14 in ST1.
Is supplied to the base of the transistor 22 so that the excitation phases (A phase, B phase, C phase,
D phase) in order.

After supplying the drive control signal (drive pulse) to each of the excitation phases, the counting of 2.5 ms is started.

At this time, for example, as shown in FIGS. 3C and 3D, the waveforms of the cathode voltage VR and the step-out detection voltage VS of the A-phase constant voltage diode 27 are such that the drive control signal VA from the CPU 11 is turned on. When it changes from to off, back electromotive force is generated. This back electromotive force is limited for a certain time Tn by the voltage of the power supply terminal Vcc and the Zener voltage of the constant voltage diode 27, and then gradually decreases.

Next, when the counter counts 2.5 ms in ST2, each excitation phase (A phase, B phase, C phase, D phase) of the stepping motor 11 is further driven by one step in ST3.

[0050] Then, for example, in each excitation phase, after supplying a driving control signal (drive pulse) respectively, the counter at S T4 counts the 0.6 ms (timing shown in FIG. 3 B), ST5 at I / The output of the O port 13 is read, and it is determined whether or not this port output P is 0, that is, whether or not the step-out detection voltage VS is lower than the reference voltage.

This determination is made because, when the stepping motor 21 steps out, the waveforms of the cathode voltage VR of each constant voltage diode 27 and the step-out detection voltage VS are as shown in FIG.
As shown in (f) and (g), the time limit Tm is shorter than the time limit Tn in the normal driving, so that the voltage at the time of step-out is smaller than the voltage during the normal driving between the time limits Tm and Tn. This is because the voltage becomes lower than the voltage.

If it is determined in step ST5 that the step-out detection voltage VS is lower than the reference voltage (port output P = 0), it is determined that step-out has occurred in the stepping motor 11, and the step-out detection control ends.

On the other hand, when it is determined that the step-out detection voltage VS is equal to or higher than the reference voltage (port output P = 1), it is determined that the stepping motor 21 is not out of step (step-out detection determining means). , And returns to the control operation of ST2.

In this embodiment having such a configuration, when detecting the step-out of the stepping motor 21, first, the respective excitation phases (A-phase, B-phase, C-phase, D-phase) of the stepping motor 21 are detected.
Phase) is driven one step at a time, 2.5
When the counting of ms is completed, each excitation phase of the stepping motor 21 is further driven one step at a time.

Thereafter, when the counting of 0.6 ms is completed for each excitation phase, the output of the I / O port 13 is read, and whether or not this port output P is 0, that is, the step-out detection voltage VS is lower than the reference voltage Is determined.

At this time, when the stepping motor 21 is operating normally, the step-out detection voltage VS becomes higher than the reference voltage, and the port output P becomes 1. Thus, it is determined that the stepping motor 21 has not stepped out.
In this case, the above processing, that is, the drive control processing of the stepping motor 21 and the step-out detection control processing thereof are repeated.

If step-out or the like occurs during the normal driving of the stepping motor 21, the step-out detection voltage VS becomes lower than the reference voltage, and the port output P becomes zero. Accordingly, it is determined that the stepping motor 21 has stepped out, and the drive control of the stepping motor 21 and the step-out detection control are ended.

As described above, when stepping out of the stepping motor 21 is performed, the step-out detection is performed by utilizing the property that the back electromotive force generated in each excitation phase is different from that during the normal driving. Since it is possible to determine whether or not the stepping motor 21 is out of synchronization with a large detection voltage, it is possible to reliably detect out-of-step.

Next, another embodiment in which the present invention is applied to an out-of-step detecting apparatus for an electronic device having a unipolar stepping motor will be described with reference to FIGS. The same parts as those in the above embodiment are denoted by the same reference numerals, and detailed description will be omitted.

FIG. 4 is a circuit diagram showing the configuration of this embodiment.
The difference from the circuit shown in FIG. 7 is that a constant voltage diode 31 is connected to the connection point between the constant voltage diode 27 and the resistor 28 with the polarity shown in the figure, and the cathode of the reverse current prevention diode 25 is connected to the cathode of this constant voltage diode 31. Is a point.

FIG. 5 shows the stepping motor 2 shown in FIG.
15 is a block diagram showing a configuration of a control unit of the first embodiment. The difference from the control unit shown in FIG.
6 is directly connected to the I / O port 13 without passing through the I / O port 13 .

This is because when the resistance values of the resistors 28 and 29 are set so that the step-out detection voltage VSS when the voltage is equal to or higher than the zener voltage of the constant voltage diode 31 becomes the logic voltage level 5 V, as described later. This is because the comparator 16 becomes unnecessary.

When the step-out detection voltage VSS is 5 V, the I / O port 31 of this embodiment has a port output P of 1;
When the step-out detection voltage VSS is 0 V, the port output P becomes 0
It is supposed to be.

The step-out detection voltage VSS changes as shown in FIG. 6D when the stepping motor 21 is normally driven, and changes as shown in FIG.

That is, when the drive control signal VA from the CPU 11 changes from on to off, back electromotive force is generated. This back electromotive force is limited for a certain time Tn by the voltage of the power supply terminal Vcc and the Zener voltage of the constant voltage diode 27, and then gradually decreases.

At this time, when the cathode voltage VR of the constant voltage diode 27 is higher than the Zener voltage of the constant voltage diode 31, the resistors 28 and 29
, A voltage obtained by subtracting the Zener voltage of the constant voltage diode 31 from the cathode voltage VR.

When the cathode voltage VR of the constant voltage diode 27 drops and becomes lower than the zener voltage of the constant voltage diode 31, no voltage is applied to the resistors 28 and 29 due to the zener characteristics of the constant voltage diode 31.

When a voltage is supplied to the resistors 28 and 29, that is, the cathode voltage V
The resistors 28 and 29 are set so that the step-out detection voltage VSS becomes 5 V when R is equal to or higher than the zener voltage of the constant voltage diode 31.
Is set, the step-out detection voltage VSS has a substantially pulse waveform of a logic voltage level (0 V to 5 V).

As described above, the step-out detection voltage VSS
The limit time Tm for normally shorter than the limit time Tn during driving, while the normal voltage at the time of driving becomes 5V is between limit time Tm-Tn, voltage at the time of loss of synchronism becomes 0V.

In this embodiment, the step-out detection is performed by detecting the step-out detection voltage VSS between Tm and Tn. That is, the CPU 11 in this embodiment performs the same control as the step-out detection control shown in FIG.

In this embodiment having such a configuration, when detecting the step-out of the stepping motor 21, first, each excitation phase (A
Phase, B phase, C phase and D phase) are driven by one step,
When the counting of ms ends, each excitation phase of the stepping motor 21 is further driven by one step.

When the counting of 0.6 ms is completed, the output of the I / O port 13 is read, and it is determined whether or not this port output P is 0, that is, whether or not the step-out detection voltage VSS is 0 V. .

At this time, when the stepping motor 21 is operating normally, the step-out detection voltage VSS becomes 5 V, and the port output P of the I / O port 13 becomes 1. Thus, it is determined that the stepping motor 21 has not stepped out. The above processing, that is, the stepping motor 2
The drive control of step 1 and its step-out detection control are repeated.

If step-out or the like occurs during the normal driving of the stepper 21 , the step-out detection voltage VSS becomes 0 V, and the port output P of the I / O port 13 becomes 0. Thereby, the stepping motor 2
1 is determined to be out of step, and the drive control of the stepping motor 21 and the out-of-step detection control are terminated.

As described above, when stepping out of the stepping motor 21, step-out detection is performed by utilizing the property that the back electromotive force generated in each excitation phase is different from that during normal driving, thereby detecting step-out compared to the conventional case. Since the out-of-step determination can be performed with a large detection voltage, the out-of-step detection can be reliably performed.

Further, a constant voltage diode 31 is connected to the connection point between the constant voltage diode 27 and the resistor 28 with the polarity shown in FIG. 4, and the cathode of the constant voltage diode 31 is connected to the cathode of the diode 25 for preventing reverse current. Therefore, when the cathode voltage VR of the constant voltage diode 27 becomes lower than the Zener voltage of the constant voltage diode 31, the resistance 28
And 29 are not energized.

As a result, even if the resistance values of the resistors 28 and 29 are increased, an increase in power consumption can be prevented as much as possible. In addition, the step-out detection voltage VSS can be easily set to a logic voltage level (0 V to 5 V) which is easier to detect than the conventional case. Therefore, more accurate step-out detection can be performed.

Further, since the step-out detection voltage VSS can be determined to be step-out detection by a pulse waveform of a logic voltage level (0 V to 5 V), the stepping motor 21 has individual variations in coil specifications and the load applied to the stepping motor 21. Can be detected without being affected by the variation in As a result, it is possible to reliably perform step-out detection.

Further, since the step-out detection voltage VSS can be determined to be step-out detection with a relatively large voltage, it is not necessary to separately provide a high-precision amplifier circuit for amplifying the step-out detection voltage VSS. Can be suppressed.

Next, another embodiment in which the present invention is applied to an out-of-step detecting apparatus for an electronic device having a unipolar stepping motor will be described with reference to FIGS.
The same parts as those in the above embodiment are denoted by the same reference numerals, and detailed description will be omitted.

FIG. 7 is a circuit diagram showing the configuration of the present embodiment.
3 is different from the circuit shown in FIG. 5 in that a backflow prevention diode 25 is provided for each excitation phase of the stepping motor, and only one counter electromotive voltage detection circuit 26 is provided for each excitation phase. Constant voltage diodes 27 and 3
The point is that all the cathodes of the backflow prevention diodes 25 of the respective excitation phases are connected to one cathode.

The step-out detection voltage VSSS in this case is shown in FIG.
It changes as shown in (e). That is, if the zener voltages of the constant voltage diodes 27 and 31 are set so that the peak voltage time of the step-out detection voltage VSSS becomes equal to or longer than the time corresponding to one step, the stepping motor 2
1 is normally driven, this step-out detection voltage VSSS
Is almost constant because the peak voltages of the step-out detection voltages of the respective excitation phases overlap.

Further, when step-out occurs in the stepping motor 21, the peak voltage of the step-out detection voltage at that time becomes shorter than that at the time of normal driving, and therefore, a portion of 0 V is generated only at this time.

FIG. 8 shows the stepping motor 2 shown in FIG.
1 is a block diagram showing the configuration of a control unit, which differs from the control unit shown in FIG. 5 in that a latch port 41 having a latch function is connected instead of the I / O port 13.

The CPU 11 in this embodiment performs step-out detection control as shown in FIG. That is, the CPU 11 first sets the motor drive circuit 1 in ST11.
4 (a), (b), (c) and (d) through FIG.
By supplying a drive control signal (drive pulse) as shown in the following to the base of the transistor 22, each excitation phase (A phase, B phase, C phase, D phase) of the stepping motor 21 is driven one step at a time. Then, after supplying a drive control signal (drive pulse) to each of the excitation phases, 2.5 ms
Start counting.

At this time, the constant voltage diode 2 of each excitation phase
As shown in FIG. 10E, the waveforms of the cathode voltage VR and the out-of-step detection voltage VSSS of FIG. 7 show that the peak voltage of the out-of-step detection voltage is continuous and substantially constant during normal driving.

Next, when the counter counts 2.5 ms for each excitation phase in ST12, in step ST13 each excitation phase (A phase, B phase, C phase) of the stepping motor 21 is further increased.
, D phase).

Then, the output of the latch port 41 is read in ST14, and it is determined whether or not the output P of the latch port 41 is 0, that is, whether or not the step-out detection voltage VSSS is 0V. At this time, if it is determined that the step-out detection voltage VSSS is 0 V (port output P = 0), it is determined that step-out has occurred in the stepping motor 21, and the step-out detection control is terminated.

On the other hand, if it is determined that the step-out detection voltage VSSS is 5 V (port output P = 1), it is determined that the stepping motor 21 has not stepped out, and the process returns to the control operation of ST12.

In this embodiment having such a configuration, when detecting the step-out of the stepping motor 21, first, the respective excitation phases (A-phase, B-phase, C-phase, D-phase) of the stepping motor 21 are detected.
Is driven by one step, and when the counting of 2.5 ms is completed, each excitation phase of the stepping motor 21 is further driven by one step.

Then, the output of the latch port 41 is read, and it is determined whether or not this port output P is 0, that is, whether or not the step-out detection voltage VSSS is 0V.

At this time, when the stepping motor 21 is operating normally, the step-out detection voltage VSSS becomes 5 V and the port output P becomes 1. Thus, it is determined that the stepping motor 21 has not stepped out. The above processing, that is, the drive control of the stepping motor 21 and the step-out detection control thereof are repeated.

[0093] The stepping over data 21, in the middle of performing such a normal driving, the step-out or the like occurs, becomes out detection voltage VSSS is 0V, the port output P is 0. Accordingly, it is determined that the stepping motor 21 has stepped out, and the drive control of the stepping motor 21 and the step-out detection control are ended.

As described above, when the stepping motor 21 loses synchronism, the step-out is detected by utilizing the property that the back electromotive force generated in each excitation phase is different from that in the normal drive, thereby detecting the loss of synchronism. Since the out-of-step determination can be performed with a large detection voltage, the out-of-step detection can be reliably performed.

A constant voltage diode 31 is connected to the connection point between the constant voltage diode 27 and the resistor 28 with the polarity shown in FIG. 4, and the cathode of the diode 25 for backflow prevention is connected to the cathode of the constant voltage diode 31. Therefore, when the cathode voltage VR of the constant voltage diode 27 becomes lower than the Zener voltage of the constant voltage diode 31, the resistance 28
And 29 are not energized.

As a result, the resistance 28
And 29, the increase in power consumption can be prevented as much as possible. Further, the out-of-step detection voltage VSSS can be easily set to a logic voltage level (0 V to 5 V) that is easier to detect than in the past. Therefore, more accurate step-out detection can be performed.

Further, since the step-out detection voltage VSSS can be judged as step-out detection based on a pulse waveform of a logic voltage level (0 V to 5 V), the stepping motor 21 has individual variations in coil specifications and the load applied to the stepping motor 21. Can be detected without being affected by the variation in As a result, it is possible to reliably perform step-out detection.

Further, by setting the zener voltages of the constant voltage diodes 27 and 31 so that the peak voltage time of the step-out detection voltage VSSS is equal to or longer than the time corresponding to one step, the stepping motor 21 is driven out of normal operation. The tone detection voltage VSSS can be made substantially constant. As a result, the step-out detection voltage VSSS can be made substantially a pulse signal only when a step-out occurs, so that the step-out detection can be reliably performed.

Further, as described above, the step-out detection voltage VSSS becomes a pulse signal only when a step-out occurs, and the step-out detection voltage VSSS is input from the latch port 41 having a latch function. It is possible to constantly monitor the detection output from the output port. This eliminates the need for the fine setting of the detection time of the step-out detection voltage VSSS as in the above embodiment.

Further, since the step-out detection voltage VSSS can be determined to be step-out detection by a relatively large voltage, the step-out detection voltage VSSS
It is not necessary to separately provide a high-precision amplifier circuit for amplifying the signal, and therefore, an increase in cost can be suppressed.

In the present embodiment, the case where only one common back electromotive voltage detection circuit 26 is provided for the four phases has been described. However, the present invention is not limited to this. It may be divided into two sets of B phase and D phase, and one set may be provided with one common back electromotive voltage detection circuit. In this case, the zener voltages of the constant voltage diodes 27 and 31 may be set such that the peak voltage of the step-out detection voltage VSSS is equal to or longer than the time during which each excitation phase is on.

Further, in this embodiment, a case where the present invention is applied to a two-phase excitation stepping motor has been described. However, the present invention is not limited to this.
The present invention may be applied to a two-phase excitation stepping motor. In this case, the out-of-step detection voltage may be detected after a certain period of time has elapsed since each excitation phase was turned off.

Next, another embodiment in which the present invention is applied to an out-of-step detecting device of an electronic device having a unipolar stepping motor will be described with reference to FIGS. The same parts as those in the above embodiment are denoted by the same reference numerals, and detailed description will be omitted.

FIG. 11 is a circuit diagram showing the configuration of this embodiment. The difference from the circuit shown in FIG. 4 is that the anode of the constant voltage diode 27 of the back electromotive voltage detection circuit 26 is connected to the motor drive power supply Vc.
(For example, 32 V) and the voltage of the step-out detection voltage VDD, which is a voltage dividing point of the resistance voltage dividing circuit (resistors 28 and 29), is compared with a preset reference voltage to compare the step-out detection voltage. The difference is that a comparison circuit 51 for detecting the time limit of VDD and outputting it to the CPU 11 is provided.

The comparison circuit 51 includes a comparator 52 for inputting the step-out detection voltage VDD from the inverting terminal (-). The non-inverting terminal (+) of the comparator 52 is connected to a voltage dividing point of a resistive voltage dividing circuit (resistors 53 and 54) connected between the power supply terminal Vcc (5V) and the ground. The resistor 55 is connected between the non-inverting terminal (+).

The output terminal of the comparator 52 is connected to the power supply terminal Vcc, and the output from this output terminal is
It is supplied to the CPU 11 via the / O port 13. The CPU 11 includes the comparator 52
13, that is, a memory 56 as detection time storage means for preliminarily storing a time limit of the step-out detection voltage VDD as shown in FIG. 13E is connected via a bus line.

The step-out detection voltage VDD changes as shown in FIG. 13D when the stepping motor 21 is driven normally, and changes as shown in FIG. 13G when step-out occurs.

That is, when the drive control signal VA from the CPU 11 changes from on to off, back electromotive force is generated. This back electromotive force is limited for a fixed time by the voltage of the power supply terminal VDD and the Zener voltage of the constant voltage diode 27, and then gradually decreases.

At this time, when the cathode voltage VR of the constant voltage diode 27 is equal to or higher than the Zener voltage of the constant voltage diode 31, the resistors 28 and 29
, A voltage obtained by subtracting the Zener voltage of the constant voltage diode 31 from the cathode voltage VR.

When the cathode voltage VR of the constant voltage diode 27 drops and becomes lower than the zener voltage of the constant voltage diode 31, no voltage is applied to the resistors 28 and 29 due to the zener characteristics of the constant voltage diode 31.

When a voltage is supplied to the resistors 28 and 29, that is, the cathode voltage V
The resistors 28 and 29 are set so that the step-out detection voltage VDD becomes 5 V when R is equal to or higher than the zener voltage of the constant voltage diode 31.
, The step-out detection voltage VDD has a substantially pulse waveform of a logic voltage level (0 V to 5 V).

The comparison circuit 51 in this embodiment detects a time equal to or longer than the reference voltage aV, and uses this detection time as the time limit of the above-mentioned step-out detection voltage VDD as shown in FIG.
The comparator output voltage VOP as shown in FIG.
11 is supplied.

The time limit TP at the time of step-out as shown in FIG. 13 (i) is shorter than the clamp time TO at the time of normal driving as shown in FIG. 13 (e). In this embodiment, performs the step-out detection by comparing the limit time T and the time limit TO during normal driving.

That is, the CPU 11 in the present embodiment
Performs step-out detection control as shown in FIG. First, in ST21, the CPU 11 supplies a drive control signal (drive pulse) as shown in FIG. 13A to the base of the transistor 22 through the motor drive circuit 24 to thereby control each excitation phase (A) of the stepping motor 21.
, B, C, and D phases) in order.

Then, in ST22, the time limit T from the step-out detection voltage VDD and the normal driving time stored in the memory 56 are stored.
A comparison is made with the time limit TO to determine whether or not the current time limit T is shorter than the time limit TO for normal driving (step-out determining means). The determination of the size of the time limit T is performed, for example, for each limited portion of the step-out detection voltage VDD.

At this time, if it is determined that the current time limit T is shorter than the time limit TO for normal driving, it is determined that the stepping motor 21 has lost synchronism, and the respective excitation phases of the stepping motor 21 are determined in ST23. Control to stop driving the motor.

[0117] In this embodiment thus constructed, when to store the time limit TO of out detection voltage VDD during energization driving of the stepping motor 21 in the memory 56, when driving the stepping motor by comparison circuit 51 The time limit of the step-out detection voltage VDD is detected, and the result is stored in the memory 56.

Thus, the time limit for the step-out detection voltage VDD when the stepping motor 21 is energized can be automatically stored in the memory 56. Therefore, it is possible to accurately measure the time limit T during the normal driving of the stepping motor 21.

When the stepping motor 21 is driven, the time limit T of the step-out detection voltage VDD is compared with the time limit TO for normal driving stored in the memory 56, and the current time limit T is set to the normal drive time. When the time is less than the time limit TO, the stepping motor 21 is determined to have lost synchronism, and the stepping motor 21 is stopped.

[0120] Thus, for detecting the time limit T of the out-of-step detecting voltage VDD when the motor driving is performed step-out determination of the time limit T is compared with the time limit TO during normal driving directly, the above-described In addition to the effect of the example, there is an effect that the out-of-step determination can be performed more reliably.

In this embodiment, the anode of the constant voltage diode 27 of the back electromotive voltage detection circuit 26 is connected to the motor drive power supply Vc. However, the present invention is not limited to this. As in the example, the anode of the constant voltage diode 27 of the back electromotive voltage detection circuit 26 may be connected to the power supply voltage Vcc (for example, 5 V).

[0122]

As described above in detail, according to the present invention, a step-out detection device which can reliably detect a step-out and can be provided at a low cost can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of one embodiment of the present invention.

FIG. 2 is a flowchart showing a step-out detection control operation in the embodiment.

FIG. 3 is a diagram showing timing of step-out detection control in the embodiment.

FIG. 4 is a diagram showing a circuit configuration of another embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a control unit in the embodiment.

FIG. 6 is a diagram showing timing of step-out detection control in the embodiment.

FIG. 7 is a diagram showing a circuit configuration of another embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a control unit in the embodiment.

FIG. 9 is a flowchart showing a step-out detection control operation in the embodiment.

FIG. 10 is a view showing timing of step-out detection control in the embodiment.

FIG. 11 is a diagram showing a circuit configuration of another embodiment of the present invention.

FIG. 12 is a flowchart showing a step-out detection control operation in the embodiment.

FIG. 13 is a view showing timing of step-out detection control in the embodiment.

FIG. 14 is a diagram showing a circuit configuration of a conventional step-out detection device.

FIG. 15 is a diagram showing a configuration of a control unit of a conventional step-out detection device.

FIG. 16 is a timing chart of the step-out detection control of the conventional step-out detection device .
Shows a ring.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... CPU 21 ... Stepping motor 22 ... Exciting transistor 25 ... Backflow prevention diode 27, 31 ... Constant voltage diode 28, 29 ... Resistance 51 ... Comparison circuit 52 ... Comparator 56 ... Memory

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02P 8/00

Claims (3)

(57) [Claims] 1. A path and a stepping motor for driving by exciting the plurality of excitation phases in on-off operation of the excitation transistor, the waveform of the counter electromotive voltage generated in the excitation phase
A back electromotive voltage detection circuit formed by connecting a series circuit of a pair of constant voltage diodes having a cathode connected to each other and a resistance voltage dividing circuit to a power supply terminal, an excitation phase of the stepping motor, the excitation transistor, At the connection point of
Connect over de, a backflow preventing diode connected to the cathode to a cathode connection point of the constant voltage diode of the counter electromotive voltage detection circuit occurs dividing point of the resistor divider of the counter electromotive voltage detection circuit A step-out detection voltage having a pulse waveform is monitored, and the time width of the step-out detection voltage is determined by the stepping mode.
A step-out detection means for judging that the stepping motor has step-out when the time is shorter than the time width during normal driving of the motor. 2. The excitation phase and the excitation transistor
Of the backflow prevention diode
Connect the anodes separately and connect all these backflow protection
Connect the common terminal connected to the cathode of the anode to the back electromotive force
Connect to the cathode of each constant voltage diode of the detection circuit,
When the stepping motor is energized, the stepping motor
The head of the back EMF waveform generated in each excitation phase of the motor.
Each constant voltage so that the time limited to a constant voltage value is continuous
2. The step-out detecting device according to claim 1 , wherein a Zener voltage of the diode is set . 3. An on-off operation of an exciting transistor.
Stepper driven by exciting multiple excitation phases
Motor and a pair of constant voltages with cathodes connected to each other
Connect a series circuit of a diode and a resistor divider to the power supply terminal.
Back electromotive voltage detection circuit, the excitation phase and the excitation
Connect the anode to the connection point with the transistor for
The cathode of each constant voltage diode of the back electromotive voltage detection circuit
A backflow prevention diode with a cathode connected to the
Deviation occurring at the voltage dividing point of the resistance voltage dividing circuit of the back electromotive voltage detection circuit
The step-out detection is performed by comparing the key detection voltage with a preset reference voltage.
Comparison circuit that detects the time when the detection voltage is higher than the reference voltage
And the comparison time when the stepping motor is energized.
Detection time storage means for storing a detection time from a road;
When the stepping motor is driven, a signal from the comparison circuit
Monitoring the detection time, the detection time from this comparison circuit and the
Detection time during normal drive taken from the detection time storage means
And the detection time from the comparison circuit is normally driven.
When the stepping motor is shorter than the detection time
A step-out determining means for determining that the step-out has occurred .