JP2002291294A - Drive circuit of stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent abnormal operation of a motor by enabling rapid and reliable detection of anomalies both in a direction of increase in a total current and in a direction of a decrease in the total current. SOLUTION: Voltages VM and VG, which are supplied to a feed point, are divided in a comparison reference voltage generating part 52 so as to generate a lower-limit voltage VH of the feed point in a case, where P1 is judged normal in an on-state, and an upper-limit voltage VL of the feed point in a case where N1 is judged as normal in the on-state. A voltage Va of the feed point (a) is input to a noninverting input of a comparator 54. 'H' is output in a case of a noninverting input voltage is larger than the noninverting input voltage, and 'L' is output in a case where the noninverting input voltage is smaller than the noninverting input voltage. Agreement or disagreement between output of the comparator 54 and a signal SEL1 is judged by an exclusive OR gate 55 so as to make the output input into an AND gate 56. A signal MSK1 is also input into the AND gate 56 in order to be output as a signal EM1.

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 detecting an abnormality in a direction in which the total current increases and also detecting an abnormality in a direction in which the total current decreases, thereby detecting an abnormal operation of the stepping motor. The present invention relates to a driving circuit for a stepping motor capable of performing prevention.

[0002]

2. Description of the Related Art A conventional driving device having a function of detecting abnormality of a stepping motor is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-9 / 1995.
No. 9796. The ones in this publication are:
A simple circuit that reliably detects disconnection or short-circuit of the coil, and focuses on the fact that one terminal of the coil is held at a high voltage even if the switching element is turned off when the coil is disconnected. Thus, disconnection detection is made possible, and disconnection detection of the four coils is performed by one-input abnormality detecting means.

At present, a four-phase excitation system in which the generated torque per consumed current is the largest is widely used for driving a five-phase stepping motor, and the generated torque is controlled by a constant current control of the driving current.

FIG. 9 is a diagram showing a conventional example of a drive circuit for a five-phase stepping motor. A switching element Q1, which is a component of the current control unit 1, is a P-type FET (field-effect transistor). P1 to P5 for supplying an exciting current to the motor 6 are P-type FETs, and N1 to N5
Is an N-type FET.

The positive electrode of the motor power supply Vm is connected to the switch element Q
1 and the negative electrode is grounded. The output signal SQ1 of the current control signal generator 11 is connected to the gate of the switch element Q1, and the drain is connected to one end of the coil L. A capacitor C is connected to the other end of the coil L1.
1 is connected, and the other end is connected to the sources of the switch elements N1 to N5.

The sources of the switching elements P1 to P5 are connected to the positive electrode of the capacitor C1. The drains of the switch elements P1 to P5 are connected to the switch elements N1 to N
5 are connected to respective drains, and are also connected to power supply points A to A of the stepping motor.

The stepping motor 6 has five sets of exciting windings A, B, C, D, and E.
B → C → D → E → A (or A → E → D → C → B →
The windings A to E are annularly connected as shown below in the order of A). The end of the winding A and the beginning of the winding C are connected to form a feeding point A. The end of the winding C and the end of the winding E are connected to form a feeding point A. And the beginning of winding B are connected to form a feeding point c, and the end of winding B and winding D
And the end of winding D and the beginning of winding A are connected to form a feeding point d.

[0008] The feeding point A is connected to the switching elements P1 and N1.
, And similarly, the feeding points I to O are
They are respectively connected to the drains of the switch elements P2 to P5 and N2 to N5.

The sources of the switch elements N1 to N5 are all connected to one end of the resistor R1 and are also input to the current control signal generator 11. The other end of the resistor R1 is grounded. The voltage Vr is supplied to the current control signal generator 11.
ef has been input.

The excitation signal generator 2 receives a signal DIR and a signal MCLK. The signals SP1 to SP5 are output from the excitation signal generation unit 2, and the signals SP1 to SP5 pass through the voltage conversion unit 4.
1 to 51 are connected to the gates of the switch elements P1 to P5, respectively. The positive voltage VM of the capacitor C1 is input to the voltage converter 4. The signals SN1 to SN5 are also output from the excitation signal generation unit 2, and the signals S1 to S5 are output through the voltage conversion unit 5.
N11 to N51 are connected to the gates of the switch elements N1 to N5, respectively.

[Explanation of Outline of Current Control Operation] A reference voltage Vref corresponding to a control target value of the total current i of the motor drive current is input to the current control signal generation unit 11, and the value is determined according to a desired torque. To set. The excitation signal generation unit 2 causes the switch element to apply a voltage to the feeding point in a predetermined order (details will be described later), whereby a current flows through the motor winding, and the total current i of the winding current is applied to both ends of the resistor R1. To generate a voltage VR1. This VR1 is compared with the Vref current control signal generation unit 11, and based on the result, the signal S
Generate Q1.

In the following description, the positive-side voltage of the capacitor C1 is referred to as VM, the negative-side voltage is referred to as VG, and the voltage difference between both ends of the capacitor is referred to as VC (= VM-VG). Signal SQ1
Accordingly, the source and drain of the switch element Q1 are repeatedly turned on (conducting) and off (cut off), and the current supplied from the motor driving power supply Vm to L is adjusted.

If the total current i of the winding currents is smaller than the target current, VR1 <Vref, and the signal SQ1 is changed so that the ON period of the switching element Q1 is lengthened. As a result, the positive voltage VM of the capacitor C1 is reduced. And the total current i of the winding current increases.

When the total current i of the winding current is larger than the target current, VR1> Vref, and the signal SQ1 is changed so that the ON period of the switching element Q1 is shortened. As a result, the positive voltage VM of the capacitor C1 is reduced. Then, the total current i of the winding current decreases. Thus, the total current i
Is almost controlled to the target value. Although VR1 changes depending on the magnitude of the total current i, since the resistance value of R1 is a very small value, VR1 <VC1, and thus VC1 扱 VM.

[Outline of Operation of Rotational Drive] A signal DIR for determining a rotational direction and a signal MCLK for determining a rotational speed are input to the excitation signal generator 2 as control signals for rotationally driving the stepping motor 6. . The excitation signal generation unit 2 generates control signals SP1 to SP5 and NP1 to NP5 for rotationally driving the motor based on these two signals, and switches the switch elements in a predetermined order to switch the motors. The windings are excited in a predetermined order, and a rotor (not shown) is rotationally driven in a rotational direction according to the signal DIR at a speed according to the signal MCLK.

Each of the feeding points A to O is connected to a switch element P1.
The positive side (hereinafter referred to as + side) of the capacitor C1 by 5
Are turned on and off, and the switching elements N1 to N5 turn on and off the negative side (hereinafter referred to as the "-" side) of the capacitor C1.

As a result, each of the power supply points is either connected to the + side or connected to the-side. As will be described in detail later, at a change point between the state connected to the + side and the state connected to the-side, there is a state in which the circuit is not connected to either for a short period of time.

The excitation signal generator 2 is a digital logic circuit of a binary operation and is composed of a gate array or the like. In this embodiment, 0 volt is output as the voltage corresponding to the off state, and the excitation signal generator 2 is output as the voltage corresponding to the on state.
5 volts, which is the power supply voltage of

The P-type FETs of the switch elements P1 to P5 operate as follows. If the gate voltage is lower than the source voltage and the difference is equal to or more than the threshold, the source-drain is turned on (conducting). If the difference between the gate voltage and the source voltage is smaller than the threshold or the gate voltage is higher than the source voltage, the source-drain is turned off (cut off).

In this embodiment, when the threshold is set to 2 volts and the transistor is turned on, the gate-source voltage is set to-
When the transistor is turned off at 10 volts (the gate voltage is 10 volts lower than the source voltage), the gate-source voltage is set at 0 volt (the gate voltage is the same as the source voltage). However, the + side voltage V
Since M, that is, the source voltage changes, the voltage converter 4
Is converted as follows based on the + side voltage.

The on-state input of 5 volts is converted to "VM-10 volts" and output. OFF input 0 volts to VM
And output. N-type FE of switch elements N1-5
T operates as follows. If the gate voltage is higher than the source voltage and the difference is equal to or greater than the threshold, the source-drain is turned on. If the difference between the gate voltage and the source voltage is smaller than the above or the gate voltage is lower than the source voltage, the source-drain is turned off.

In this embodiment, when the threshold is set to 2 volts and the ON state is set, the gate-source voltage is set to 1
When the transistor is turned off at 0 volt (the gate voltage is higher than the source voltage by 10 volts), the gate-source voltage is set at 0 volt (the gate voltage is the same as the source voltage).

The voltage is converted by the voltage converter 5 as follows. The on-state input of 5 volts is converted to 10 volts and output. The 0 volt input at the time of off is output as it is at 0 volt.

[Explanation of Operation of Excitation Drive] FIG.
FIG. 9 is a diagram showing four-phase excitation driving of a five-phase stepping motor,
The feeding points A to O are indicated by vertices of a pentagon, and the energized state is indicated by the following symbols. A circle is given when the voltage VM is applied when the switch elements P1 to P5 are on and the switch elements N1 to N5 are off. When the switch elements P1 to P5 are off and the switch elements N1 to N5 are on and the voltage VG is given, the symbol ● is given.

The excitation step proceeds in synchronization with the signal MCLK. The signal DIR is a signal that determines the direction of rotation. For example, when the signal DIR is “H”, the excitation step is performed in synchronization with the rise of the signal MCLK (1) (2)
(3)... (10) (1).

When the signal DIR is "L", the signal MCL
The excitation step is synchronized with the rise of K (1)
(10) (9) ... (1) (10) ...
The order is the reverse of the case of “H”, and the rotation direction is reversed.

When the signal DIR is "H" and "L", the power supply state of each excitation step is the same except for the direction of the excitation step, so that only the case of "H" will be described below. In the excitation step (1), (1a) a state in which the feed point A / O is connected to the + side and the voltage VM is applied, and the feed point A / O is connected to the − side and the voltage VG is applied; 1b) The state where the feeding point A is connected to the + side, the voltage VM is applied, and the feeding point AYU is connected to the-side, and the voltage VG is applied is alternately temporally 50%. Repeated.

That is, in step (1), the voltages VM and VG are alternately and synchronously applied to the power supply points A and A at a rate of 50%. This repetition is performed by the signal MCLK.
Is performed in a cycle sufficiently shorter than the cycle of

When the excitation step proceeds to (2), (2a)
A state in which the feeding point A / E / O is connected to the + side and the voltage VM is applied, the feeding point c is connected to the − side and the voltage VG is applied, and (2b) the feeding point A / O is the + side. Connected to the voltage V
M is supplied, the feeding point YW is connected to the negative side, and the voltage V
The state given G is alternately repeated at a rate of 50% over time.

That is, in step (2), the voltages VM and VG are alternately and synchronously applied to the power supply point Y at a rate of 50%. This repetition is performed in a cycle sufficiently shorter than the cycle of signal MCLK.

Hereinafter, similarly, the process proceeds to the excitation step (10), and then returns to the step (1). This excitation method has the advantages that a voltage is applied to both ends of the winding in each step, the current changes quickly, and the motor can be driven to rotate at a higher speed.

[0032]

In a drive circuit for a stepping motor, a malfunction or the like occurs in a switch element for some reason, and when an extremely large abnormal current flows, the element or circuit may be burned. To avoid this,
When an excessive current is detected, a configuration is often provided for taking measures such as stopping the motor driving operation and turning off the power.

For example, in the above-described conventional example, as shown in FIG. 9, a comparison unit 7 for comparing a voltage VR1 generated across the resistor R1 with a high voltage VEX which cannot be generated in a normal state is provided. Is input to the excitation signal generator 2 and the current control signal generator 11. Signal OF
F is VR1 <VEX, that is, “L” at normal time,
The excitation signal generator 2 and the current control signal generator 11 perform the normal operation as described above.

If the current flowing through R1 becomes extremely large for some reason and VR1> VEX, it is determined that an abnormality has occurred and the signal OFF is set to "H". As a result, the excitation signal generator 2 outputs the signals SP1 to SP5 and SN1 to the switch element.
-5 are all set to 0 volt, and all the switch elements are turned off. Further, the current control signal generation unit 11 also turns off Q1 to stop the current supply. Further, the current detection resistor R1
In order to detect an abnormal current that does not pass through, the configuration shown in FIG. 11 may be added to the configuration shown in FIG.

An abnormal current detecting resistor RX is inserted between the source of the motor power supply Vm and the source of Q1, and the voltage VRX generated at both ends of the RX is detected by the differential amplifier 21. A comparison unit 22 is provided for comparing VRX with a high voltage VEX2 that cannot be generated in a normal state, and the same processing as in the above example is performed using the output signal OFF2. Thereby, for example, even when the power supply point A is grounded for some reason and a very large current flows without passing through R1, it can be detected as an abnormality.

However, in these conventional configurations, since the determination is made based on the voltage difference generated between both ends of the current detection resistor,
There are the following problems. Since the current flowing through the resistor contains a large amount of spike-like high-frequency noise due to the high-speed switching operation by the above-described switching element, it is actually necessary to suppress the noise with a low-pass filter or the like.

Even if noise is suppressed by using such a filter, VEX as a criterion for determining an abnormality is set to a value considerably larger than the normal range so that the maximum current in the normal range is not erroneously determined to be abnormal. And it is difficult to improve the detection accuracy of the abnormal state. Further, an abnormality in the direction of increasing current can be detected, but an abnormality in the direction of decreasing current cannot be detected.

For example, in the above-described conventional example, when an abnormality such as the switch element P1 is not turned on and the total current decreases, the constant current control increases the VM by that amount, and the current to the remaining winding is increased. The supply increases more than normal. However, in the excitation state in which P1 does not participate, the current becomes a normal current, and the total current decreases to a normal value. In the constant current control, the VM may be changed instead of trying to correct this change. On the other hand, the motor may continue to rotate apparently due to its own rotor or the amount of inertia of the load, which may result in a delay in finding an abnormality.

The present invention has been made in view of such a problem. The purpose of the present invention is not only to detect an abnormality in the direction in which the total current increases but also to detect an abnormality in the direction in which the total current decreases, which cannot be detected in the conventional example. An object of the present invention is to provide a driving circuit for a stepping motor capable of promptly and surely detecting an abnormality and effectively preventing abnormal operation of the motor.

[0040]

In order to achieve the above object, the present invention provides a five-phase stepping motor in which five sets of windings are connected in a ring. An excitation signal generation unit that excites a plurality of phases of the stepping motor in a predetermined procedure, and detects that a power supply point voltage is in a voltage range according to a power supply state when the stepping motor is rotationally driven. It is characterized by having means.

Further, the invention described in claim 2 is the same as the invention described in claim 1.
In the invention described in (2), two types of voltage ranges, from a high potential to a slightly lower potential and a voltage range from a low potential to a slightly higher potential, are provided as voltage ranges according to the power supply state, and both ranges are not continuous. It is characterized by the following.

Further, the invention according to claim 3 provides the invention according to claim 1
Or in the invention described in 2, when the stepping motor is driven to rotate, the voltage at the power supply point is divided into a fixed ratio, and a voltage corresponding to a voltage range from a high potential to a slightly lower potential according to the division ratio. A range and a voltage range corresponding to a voltage range from a low potential to a slightly higher potential are provided, and both ranges are not continuous.

The invention described in claim 4 is the first invention.
In the invention described in (1), the detection means is always performed except during a period in which neither a high potential nor a low potential is applied to the feeding point.

[0044]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 is a diagram showing an embodiment of a driving circuit for a stepping motor according to the present invention, and is a diagram showing a configuration relating to a feeding point a. The same components as those in FIG. 9 are denoted by the same reference numerals, and the description of the portions having the same configuration is omitted. The other four power supply points a to e have the same configuration, and a description thereof will be omitted.

The comparison control signal generator 51 receives the signals SP1 and SN1 output from the excitation signal generator 2 when controlling the switch elements P1 and N1, and outputs the signals SEL1 and MSK1. .

The comparison reference voltage generating section 52 divides the voltages of VM and VG applied to the feeding point by resistors R11 to R13, and sets the lower limit voltage VH of the feeding point when P1 is determined to be normal when turned on. And an upper limit voltage VL at the feeding point when N1 is determined to be normal when turned on. For example, when VM is set to 100% based on VG, V
H is 90% and VL is 10%. As a result, even if the VM changes due to the current control, the value becomes a value corresponding to the change.

The analog switch 53 receives the input VH
And VL are selected and output by the selection signal SEL1.
That is, when SEL1 is "H", VH is output,
At the time of “L”, VL is output. Analog switch 53
Is input to the inverting input side of the comparator 54. The voltage VA at the feeding point A is input to the non-inverting input side of the comparator 54, and outputs “H” when the non-inverting input side voltage> the non-inverting input side voltage, and the non-inverting input side voltage <non-inverting voltage. In the case of the inverted input side voltage, “L” is output. Exclusive OR gate 55
, It is determined whether the output of the comparator 54 and the signal SEL1 match, and the output is input to the AND gate 56.
The signal MSK1 is also input to the AND gate 56, and the signal E
Output as M1.

Similarly, the signal E for the feeding points I to E
M2-5 are generated, which, as shown in FIG.
The signal is input to the input OR gate 57 and output as a signal OFF.

FIG. 3 is a timing chart of the configuration shown in FIG. 1 in a normal state, in which the excitation step (1) in FIG. 10, that is, (1a) and (1b) are alternately repeated. The signal MCLK does not change in the range of FIG. 3 for convenience of explanation.

Signals SP1 and SN1 for controlling switch elements P1 and N1 alternately repeat 5 volts ("H") and 0 volts ("L"). At this time, at the ON / OFF transition point, in order to prevent the P1 and N1 from being simultaneously turned on due to the switching operation delay of the switching element, etc.
A period in which both are off, that is, a dead time is provided only for a short period Δtd.

Signal SE for controlling analog switch 53
L1 changes from “L” to “H” in synchronization with the transition point (fall) of SN1 from on to off, and changes to “H” in synchronization with the transition point (fall) of SP1 from on to off. "
From “L” to “L”.

The signal MSK1 is normally at "H", and becomes "L" for a period slightly longer before and after the dead time with the dead time described above. This signal is input to the AND gate 56, and during "L", the output of the gate, that is, the signal E
M1 is set to “L”. This suppresses the output signal EM1 from fluctuating in the output of the exclusive OR gate 55 due to the variation of the voltage V near the dead time period.

In the following, for the sake of description, a period in which signal MSK1 is at "H" will be described. The signal SEL1 is "H"
During the period, VH is input to the inverting input side of the comparator 54, and this is compared with the voltage V at the feeding point A. Here, if normal, Va> VH, and the comparator 54 outputs "H".

In the exclusive OR gate 55, the comparator 54
Is output and the value "H" of the signal SEL1 is compared, and since they match, "L" is output, and the signal EM1 becomes "L", that is, "normal".

Subsequently, after a short period of time when MSK1 is "L",
This is the period when the signal SEL1 is "L". Here, VL is input to the inverting input side of the comparator 54, and this is compared with the voltage VA at the feeding point A. If it is normal here, V
A <VL, and the comparator 54 outputs “L”.

In the exclusive OR gate 55, the comparator 54
And the value "L" of the signal SEL1 are compared and output "L" because they match, and the signal EM1 becomes "L", that is, "normal".

Subsequently, after a short period of time when MSK1 is "L",
The signal SEL1 is in the "L" period, and the determination whether there is any abnormality is repeatedly performed almost always.

FIG. 4 is a diagram showing an example of the occurrence of an abnormality relating to the power supply point A, in which the switch element N1 breaks down to the OFF state even during the ON period.
(1a) of the excitation step (1) in FIG.
That is, the signal SEL1 is in a normal state while the signal SEL1 is "H", and since Va> VH, the signal EM1 is "L", that is, "normal".

Subsequently, after a short period of time when MSK1 is "L",
This is the period when the signal SEL1 is "L". During that period, N1 is supposed to be in the ON state, but if it fails off in the middle of the period, winding A and winding C are connected in series. The voltage at the connection point of C, that is, the voltage at the feeding point A starts rising from VL, and Va> VL, and the comparator 54 outputs “H”.

In the exclusive OR gate 55, the comparator 54
Does not match the value "L" of the signal SEL1 and outputs "H", and the signal EM1 immediately becomes "H", that is, "abnormal".

As a result, the signal OFF immediately becomes "H", and thereafter, as in the case of the abnormality detection in the conventional example, the excitation signal generator 2 sets all the signals SP1-5 and N1-5 to the switch elements to 0 volts and switches Turn off all elements,
Alternatively, the current control signal generation unit 11 also performs a measure such as turning off Q1 to stop the current supply, and stops the motor to stop driving the motor in an abnormal state.

In this embodiment, since the switch element fails in the direction of turning off, it apparently changes in the direction in which the total current decreases, which is an abnormality that cannot be detected by the conventional configuration.

FIG. 5 is a diagram showing another example of the occurrence of an abnormality relating to the power supply point A, in which the switch element P1 breaks down to the ON state during the step (1b), ie, during the OFF period. It is. In (1a) of the excitation step (1) in FIG. 10, that is, during the period when the signal SEL1 is "H", the signal EM1 becomes "L", that is, "normal" because Va> VH. ing.

Subsequently, after a short period of time when MSK1 is “L”,
This is the period when the signal SEL1 is "L". During that period, P1 should be in the off state, but if it breaks down in the middle of the period, the switching elements P1 and N1 are both in the on state, and the ga conduction state from the + side to the-side ga conduction state. The point, that is, the voltage at the feeding point A is the switching element P1
And the voltage divided by the ON resistance of N1.
And VM, a voltage in an intermediate range that cannot be obtained in a normal state, so that Va> VL, and the comparator 54 outputs “H”. Thereafter, the signal EM1 immediately becomes "H", that is, "abnormal", as in the above-described example, and the abnormal state is treated.

As a comparative reference voltage, it is conceivable to simply use 50%, which is the middle of the voltage difference between VM and VG, and determine the magnitude of this and VA. However, in this method, the following method is used. There is such a problem.

For example, in the same manner as in the timing chart shown in FIG. 4, when N1 fails to turn off and Va rises above a normal voltage value, as shown in FIG.
Since no abnormality can be detected until the level reaches 0%, 50
If the "H" period of SP1 is entered before reaching the% level, the detection of abnormality will be delayed until the "L" period of SN1 again.

Alternatively, in the same manner as in the timing chart shown in FIG. 5, when P1 fails to turn on and Va rises above a normal voltage value, P1 and N
(1) Even if the ratio does not exceed the 50% level due to the ratio of the resistance between the source and the drain, the detection of the abnormality is delayed. In this fault, both P1 and N1 are turned on, and a very large short-circuit current flows from the source of P1, ie, the + side to the source of N1, ie, the − side. Therefore, it is extremely dangerous to delay detection of the fault in this state.

Therefore, as in the present embodiment, the comparison reference voltage is provided with boundaries at two levels of “around VM” and “around VG”.
By comparing the voltage range that should be normal and the power supply point voltage according to the power supply state, it is possible to detect the abnormality promptly and reliably.

The value of the voltage range that should be in a normal state is as follows:
In consideration of the motor driving conditions and the like, the narrower the setting, the better the accuracy of detecting an abnormality.

[Second Embodiment] FIG. 7 is a diagram showing a configuration related to a power supply point A for explaining a second embodiment of the drive circuit of the stepping motor according to the present invention. FIG.
The same components as those described above are denoted by the same reference numerals, and the description of the portions having the same configuration is omitted. The other four power supply points a to e have the same configuration, and therefore the description is omitted.

In general, the excitation signal generator 2, the exclusive OR gate 55, and the AND gate
The operation power supply voltage of such a digital logic circuit is as low as, for example, about 5 volts. However, the drive power supply voltage Vm or VM of the motor is often 20 volts or more, which is much higher than the power supply voltage of the digital section, depending on the specifications and drive load conditions of the motor.
In such a case, instead of using the feed point voltage directly, use a voltage that is divided from the feed point a to the negative side using a resistor, and in such a case, the maximum value falls within the range of the digital power supply voltage. By setting the voltage division ratio, an analog switch or a comparator can be configured with a general-purpose product having an input voltage range of a digital power supply voltage range. This embodiment is a configuration in that case, and is the same as the first embodiment except that the feeding point voltage is divided and used.

In this embodiment, the power supply voltage VD of the digital logic circuit is 5 volts, VM is much higher than VD,
It is also assumed that the value changes in a certain voltage range by current control.

The feed point voltage VA is equal to the resistance R3
1 and R32 to be a voltage V1. As described above, although the VM changes due to the current control, the voltage division ratio is set so that the voltage V1 does not exceed 5 volts within the range of the change. At this time, the resistance values of R31 and R32 are set as high as possible so as not to affect the power supply operation.

For example, when the VM rises to a maximum of 50 volts, the voltage is divided into one tenth and R31 on the VG side is set to one.
If 0 kΩ and R32 on the feeding point side are 90 kΩ, V
Ranges from 5 volts to VG (almost 0 volts).

The comparison reference voltage generation section 52A divides the voltages of VM and VG applied to the feeding point by the resistors R21 to R23, and sets the lower limit voltages VH and N1 when it is determined that P1 is normal when ON. The upper limit voltage VL, which is determined to be normal when turned on, is generated as a value corresponding to the voltage division of the voltage V. The comparison reference voltage generator 52 of the first embodiment is used.
And the setting of the comparison reference voltage is different.

In the same manner as in the first embodiment, the VM
If VH is 90% and VL is 10%, the voltage VHH corresponding to VH is 4.5 V, and
The voltage VLL corresponding to L may be set to 0.5 volt.

Thus, the analog switch 53A and the comparator 54A are functionally equivalent to the analog switch 53 and the comparator 54 of the first embodiment, respectively, but the input voltage range is from 5 volts which is the power supply voltage of the digital section. It can be composed of general-purpose products in the range of 0 volt. Subsequent functions and operations are the same as in the first embodiment.

In such a configuration, although the number of components such as a resistor for voltage division is slightly increased, there is an advantage that a wide range of VM can be handled. In the recent IC technology, the analog section such as the analog switch 53A and the comparator 54A can be configured on the same IC chip as the digital circuit such as the exclusive OR gate 55, the AND gate 56, and the excitation signal generating section 2. Practically, it can be constructed with little additional parts.

In the above-described embodiment, the description has been given of the stepping motor of the five-phase ring connection type. However, the present invention is not limited to this, and is widely applied to other types of motors such as a three-phase Y connection type stepping motor. Applicable.
Further, the present invention is not limited to the constant current control method, and has the same effect when used in a drive circuit of a constant voltage drive method.

[0080]

As described above, according to the present invention, 5
A five-phase stepping motor in which a pair of windings are connected in a ring, and an excitation signal generating unit that excites a plurality of phases of the stepping motor in a predetermined procedure. Is equipped with a detection means for detecting that the total current is in the voltage range according to the power supply state. And abnormal operation of the motor can be effectively prevented.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a 5-input OR gate according to the first embodiment.

FIG. 3 is a diagram showing a timing chart in a normal state in the first embodiment.

FIG. 4 is a diagram showing a timing chart at the time of abnormality in the first embodiment.

FIG. 5 is a diagram showing a timing chart at the time of an abnormality in the first embodiment.

FIG. 6 is a diagram showing a timing chart at the time of abnormality in a conventional example.

FIG. 7 is a diagram showing a timing chart at the time of abnormality in a conventional example.

FIG. 8 is a diagram for explaining a second embodiment of the present invention.

FIG. 9 is a diagram showing a drive circuit of a conventional five-phase stepping motor.

FIG. 10 is a diagram illustrating a four-phase excitation driving method of a five-phase stepping motor.

FIG. 11 is a diagram showing a drive circuit of a conventional five-phase stepping motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current control part 2 Excitation signal generation part 4,5 Voltage conversion part 6 Stepping motor 7 Comparison part 11 Current control signal generation part 21 Differential amplifier 22 Comparison part P1-P5 N1-N5 Switch element 51 Comparison control signal generation part 52, 52A Reference voltage generator 53, 53A Analog switch 54, 54A Comparator 55 Exclusive OR gate 56 AND gate 57 5-input OR gate

Claims (4)

[Claims] 1. A stepping motor having five phases in which five sets of windings are connected in a ring, and an excitation signal generating unit that excites a plurality of phases of the stepping motor in a predetermined procedure. A driving circuit for a stepping motor, comprising: detecting means for detecting that a power supply point voltage is in a voltage range according to a power supply state when driving. 2. A voltage range according to the power supply state,
2. The stepping motor drive circuit according to claim 1, wherein two types of voltage ranges are provided: a voltage range from a high potential to a slightly lower potential, and a voltage range from a low potential to a slightly higher potential, and both ranges are not continuous. . 3. When the stepping motor is driven to rotate, the power supply point voltage is divided into a constant ratio, and a voltage range corresponding to a voltage range from a high potential to a slightly lower potential according to the division ratio; 3. The stepping motor drive circuit according to claim 1, wherein a voltage range corresponding to a voltage range from a low potential to a slightly higher potential is provided, and both ranges are not continuous. 4. The stepping motor drive circuit according to claim 1, wherein said detecting means is always performed except during a period when neither a high potential nor a low potential is applied to said feeding point.