JPH0373239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a step motor drive device for driving a step motor.

[Prior Art] Conventionally, in a step motor drive device, the control to reduce the rotational speed of the step motor is as follows:
A so-called through-down control is known in which the switching frequency of a drive pulse signal selectively switched to each phase winding of a step motor is gradually slowed down. Also,
Another method of deceleration control is to gradually lower the excitation voltage applied to each phase winding of the step motor to lower the driving torque.

[Problem to be solved by the invention] However, in any deceleration control,
The rate of slowing down the switching frequency or the rate of decreasing the excitation voltage is determined based on the current speed and the desired speed after deceleration, so the deceleration control described above can be used when always performing the same deceleration, but it can be used when decelerating at any time. It cannot be applied to deceleration control from one speed to an arbitrary speed lower than that speed, that is, deceleration control corresponding to a wide range of rotational speeds.

Furthermore, since the deceleration control described above is performed according to predetermined data, if sudden speed fluctuations occur during control due to load fluctuations, etc., control can be performed in response to these speed fluctuations. First, there is a risk that the step motor may step out during deceleration.

The present invention has been made to solve the above problems, and is capable of performing deceleration control that corresponds to a wide range of rotational speeds, as well as being able to perform step control even if speed fluctuations occur due to load fluctuations during deceleration. It is an object of the present invention to provide a step motor drive device that does not cause a motor to step out.

[Means and operations for solving the problem] In order to achieve the above object, the invention as set forth in claim 1 provides a step motor having a plurality of phase windings, and a step motor having a plurality of phase windings. The output terminal has an output terminal connected to each phase winding so as to output an excitation current, and an input terminal for controlling the output of the output terminal, and outputs an output corresponding to the input via the input terminal. an excitation device that sequentially outputs a control signal for normal rotation drive to an input terminal corresponding to a drive element that outputs an output from a drive element, and a phase winding that is connected to the input terminal and through which an excitation current is conducted to drive the step motor in normal rotation; In a step motor drive device equipped with a phase selection circuit, the phase winding is different from the phase winding that is provided in the excitation phase selection circuit and is conducted when the step motor is driven in the normal rotation so as to apply a brake to the normal rotation drive of the step motor. A designating means for designating an input terminal corresponding to the phase winding on the reverse drive side, and connected to each of the input terminals, capable of detecting the rotational speed of the step motor and outputting an analog brake signal corresponding to the rotational speed. and a conduction means connected to the input terminal to conduct the analog brake signal output from the analog brake signal generation circuit to the input terminal designated by the designation means.

According to the present invention having such a configuration, in a step motor drive device that is driving in normal rotation, the specifying means applies a brake to the normal rotation drive so that the phase winding is different from the phase winding that is conductive during normal rotation drive. An input terminal corresponding to the side phase winding is designated, and an analog brake signal corresponding to the rotational speed that can always be outputted by the analog brake signal generation circuit is conducted to the input terminal via the conduction means.
This allows the step motor drive to provide good braking control over a wide range of rotational speeds.

According to the step motor drive circuit set forth in claim 2, the drive element set forth in claim 1 is constituted by a drive transistor circuit, and the input terminal is connected to the drive transistor circuit. Corresponding to the base, the conduction means includes a 3-state buffer gate connected to the base of the drive transistor, a backflow prevention element connected between the base of the drive transistor and the analog brake signal generation circuit, and The designation means is comprised of a gate signal generator that controls the three-state buffer gate.

In the step motor drive device having the configuration according to claim 2, when the drive transistor is turned off, that is, when the output of the 3-state buffer gate becomes LOW, the charge at the base of the drive transistor changes to the 3-state. It is discharged to the output terminal of the buffer gate, and the fall characteristics of the collector current of the drive transistor are improved.

[Example] Hereinafter, an example embodying the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit block diagram of a step motor drive device according to the present invention, in which 1 is a four-layer step motor consisting of four phase windings W1 to W4;
is an analog brake signal generation circuit.

This analog brake signal generation circuit 2 detects the rotation of the step motor 1, and as shown in FIG. SS1～SS
Detection circuit 3 outputs 4 and this sine wave signal SS
1 to SS4 are input, and each is individually composed of a resistor and a capacitor, as shown in FIG. 4a,
A differentiating circuit 4 converts the sine wave signals SS1 to SS4 into alternating current signals SD1 to SD4 whose amplitude values change in proportion to the period thereof, the alternating current signals SD1 to SD4, and the sine wave signals SS1 to SS4 from the detection circuit 3. The selection signals SM1 and SM2 output corresponding to the period are input, and the signal SE is synthesized by sequentially selecting each peak value region of the AC signals SD1 to SD4 shown in FIG. 4b using the selection signals SM1 and SM2. The multiplexer 5 outputs the signal SE, and the fourth
As shown in FIG. c, it is composed of an amplifier circuit 6 that outputs a voltage level signal SG obtained by amplifying the signal SE. 7 is four 3-state buffer gates GB
1 to GB4.

The excitation phase selection circuit sends a signal PH1 to the base terminals of drive transistors Tr1 to Tr4, which will be described later, so as to drive the step motor 1 in the normal rotation through the 3-state buffer gate 7 and the 3-state buffer gate 7. - A signal output device (not shown) that outputs PH4 and the step motor 1
The gate signal generating device (not shown) controls the three-state buffer gate 7 based on gate signals GT1 to GT4, which will be described later, so as to apply a brake to the forward rotation of the motor. The gate signal generator constitutes a designating means.

The operation of the three-state buffer gate will be explained with reference to FIG. In Figure 2, the signal
IN, OUT, and GATE are input signals, output signals, and
It is a gate signal, and when the gate signal GATE is LOW, if the input signal IN is LOW, the output signal OUT
is LOW, and if the input signal IN is HIGH, the output signal
OUT is output as HIGH and the gate signal
When GATE is HIGH, the output terminal OUT becomes high impedance regardless of the input signal IN.

Again in FIG. 1, 8 is a step motor drive circuit, and the collector terminals of each drive transistor Tr1 to Tr4 corresponding to each phase winding are connected to a resistor, a series connection of each phase winding W1 to W4, and a flywheel diode DF1. -DF4 are connected to the power supply voltage VD via a parallel circuit, and the emitter terminals of each drive transistor are commonly connected and grounded via a diode DB. Further, the voltage level signal SG from the amplifier circuit 6 is wire-ORed to each output line of the excitation phase selection circuit 7 via diodes D1 to D4 as unidirectional elements for preventing backflow and a resistor, and is connected to the drive element via the resistor. The signal is input to the base terminal as the input terminal of each drive transistor used as the input terminal.

The voltage level signal SG as the analog brake signal is input to the base terminals of the drive transistors Tr1 to Tr4 only when the output terminal of the three-state buffer gate 7 is in high impedance.
As a result, diodes D1 to D4 for backflow prevention
, the resistor, and the 3-state buffer gate 7 constitute conduction means.

Next, the operation of the excitation phase selection circuit 7 will be explained. First, when driving a step motor with two-phase excitation without a brake phase, that is, (W1, W2) - (W
2, W3)-(W3, W4)-(W4, W1)-(W
1, W2), the gate signals GT1 to GT4 are all LOW in the excitation phase selection circuit 7, and the input signal
PH1 to PH4 correspond to the excitation of the phase windings mentioned above,
As shown in Figure 6, (PH1, PH2) - (PH2,
PH3) - (PH3, PH4) - (PH4, PH1) -
(PH1, PH2) become HIGH in that order, and the other phases become LOW. At that time, the drive transistor corresponding to the phase for which the input signal is HIGH is in the ON state to excite the phase winding, and the drive transistor corresponding to the phase for which the input signal is LOW is in the OFF state, so that the phase winding is not excited.

For example, as shown in FIG. 5, between time T1 and time T2, input signals PH2 and PH3 are
HIGH and other input signals PH4, PH1
becomes LOW. At that time, input signals PH2, PH3
The drive transistors Tr2 and Tr3 corresponding to
An exciting current flows through W3, and phase windings W2 and W3 are excited. On the other hand, the drive transistors Tr4 and Tr1 corresponding to the input signals PH4 and PH1 are turned off, and as shown in FIG. 6, no excitation current flows through the phase windings W4 and W1, and the phase windings W2 and W3 are excited. Not done.

Similarly, between time T2 and time T3,
Input signals PH3 and PH4 are HIGH, and other input signals PH1 and PH2 are LOW. At that time, the drive transistors Tr3 and Tr4 corresponding to the input signals PH3 and PH4 are turned on, and as shown in FIG. 6, an excitation current flows through the phase windings W3 and W4, and the phase windings W3 and W4 are excited. . On the other hand, drive transistors corresponding to input signals PH1 and PH2
Tr1 and Tr2 are in the off state, and as shown in FIG. 6, no exciting current flows through the phase windings W1 and W2.
Phase windings W1 and W2 are not excited.

Next, when controlling the speed by exciting one phase as a brake phase in addition to two-phase excitation, that is, (W1, W2)
-(W2,W3)-(W3,W4)-(W4,W1)-
Corresponding to exciting the phase windings in the order of (W1, W2), when the phase windings are excited as the brake phase in the order of W4-W1-W2-W3-W4, the excitation phase selection circuit 7 Gate signal as shown
GT1 to GT4 are GT4-GT1-GT2-GT3-
GT4 becomes HIGH, and the others become LOW. At that time, the input signals PH1 to PH4 correspond to the phase windings, as shown in FIG.
2) - (PH2, PH3) - (PH3, PH4) - (PH
4, PH1) - (PH1, PH2) become HIGH in this order, and the other input signals become LOW. As a result, the drive transistor corresponding to the phase where the gate signal is LOW is in the on state when the input signal is HIGH, and is in the LOW state when the input signal is HIGH.
The voltage level signal of the analog brake signal generation circuit 2 is applied to the base terminal of the phase drive transistor that is in the off state when the gate signal is HIGH.
A base current corresponding to SG is input, thereby exciting its phase winding as a brake phase for brake control corresponding to the rotational speed of the step motor 1. For example, as shown in FIG. 7, between time T1 and time T2, the gate signal GT
1 becomes HIGH, and other gate signals GT2~
GT4 becomes LOW. At that time, input signal PH2,
PH3 becomes HIGH, and input signals PH1 and PH4 become
becomes LOW. This causes the gate signal to
Drive transistor Tr corresponding to the phase that is LOW
Among drive transistors Tr2, Tr3, and Tr4, the drive transistors Tr2 and Tr3 whose input signals are HIGH are turned on, and as shown in FIG.
A drive current flows through the phase windings W2 and W3, and the phase windings W2 and W3 are excited. The drive transistor Tr4 whose input signal is LOW is turned off, no excitation current flows through the phase winding W4, and the phase winding W4 is not excited.
On the other hand, as shown in FIG. 7, an analog brake signal generation circuit 2
As shown in FIG. 8, an excitation current corresponding to the voltage level signal SG flows through the phase winding W1, and the phase winding W1 is excited as a brake phase.

Similarly, between time T2 and time T3,
The gate signal GT2 becomes HIGH, and the other gate signals GT1, GT3, and GT4 become LOW. At that time, input signals PH3 and PH4 become HIGH,
Input signals PH1 and PH2 become LOW. As a result, among the drive transistors Tr1, Tr3, and Tr4 corresponding to the phase whose gate signal is LOW, the drive transistor whose input signal is HIGH
Tr3 and Tr4 are turned on, and as shown in FIG. 8, a drive current flows through the phase windings W3 and W4, and the phase windings W3 and W4 are excited. The drive transistor Tr1 whose input signal is LOW is in an off state, no excitation current flows through the phase winding W1, and the phase winding W1 is not excited. On the other hand, the gate signal is HIGH
As shown in FIG. 7, the voltage level signal SG of the analog brake signal generation circuit 2 is input to the base terminal of the drive transistor Tr2 corresponding to the phase, and as shown in FIG. An excitation current corresponding to the voltage level signal SG flows through the phase winding W2, and the phase winding W2 is excited as a brake phase.

As described above, in the step motor drive device according to the present invention, an excitation current corresponding to the rotation speed flows through the phase winding on the reverse drive side, which is different from the phase winding that is conducted during normal rotation drive, so that the step motor The brake is applied according to the rotation speed. Therefore, good deceleration control can be performed over a wide range of rotational speeds. Furthermore, even if speed fluctuations occur due to load fluctuations during deceleration, the step motor will not step out.

Furthermore, when the drive transistors Tr1 to Tr4 are turned off, that is, when the output OUT of the 3-state buffer gate becomes LOW, the charge at the base of the drive transistor is discharged to the output terminal of the 3-state buffer gate via the resistor. Therefore, the falling characteristics of the collector current of the drive transistor are improved.

Further, the power supply voltage Vcc of the analog brake signal generation circuit 2 and the excitation phase selection circuit 7 is a single power supply, so that the power supply can be configured simply.

It should be noted that the present invention is not limited to the above-described embodiments; for example, a field effect transistor (EFT) or the like may be used as the driving element, or the 3-state buffer gate may be simply composed of a semiconductor element. Instead, it may be composed of electronic components or the like.

[Effects of the Invention] As described in detail above, in the step motor drive device of the present invention, the phase winding, which is different from the phase winding that is conductive during the normal rotation drive, applies a brake to the normal rotation drive of the step motor. By outputting an analog brake signal according to the rotation speed of the step motor to the control terminal corresponding to the phase winding on the drive side, it is possible to apply good brake control over a wide range of rotation speeds, and also to reduce deceleration. It is possible to provide a step motor drive device in which the step motor does not step out even if speed fluctuations occur during the course of the step due to load fluctuations.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram of a step motor driving device according to the present invention, Fig. 2 is a block diagram of a 3-state buffer gate, and Fig. 3 is a sine wave signal SS1.
- Timing chart showing SS4, Figure 4 is a timing chart showing AC signals SD1 to SD4, signal SE, and voltage level signal SG. Figure 5 is a gate signal when driving a step motor with two-phase excitation without a brake signal. GT1 to GT4 and input signals
Timing chart showing PH1 to PH4, Figure 6 shows each phase winding W1 to W4 when driving a step motor with two-phase excitation without applying a brake signal.
7 is a timing chart showing the gate signals GT1 to GT4 and input signals PH1 to PH4 when driving the step motor with two-phase excitation by adding a brake signal, and FIG. 8 is a timing chart showing the current flowing to the brake. Each layer winding W1 when driving a step motor with two-phase excitation by applying a signal
This is a timing chart showing the current flowing through W4. In the figure, 1 is a step motor, 2 is an analog brake signal generation circuit, 7 is a 3-state buffer gate, 8 is a step motor drive circuit, D1 to D4 are diodes, and Tr1 to Tr4 are drive transistors.

Claims (1)

[Scope of Claims] 1. A step motor having a plurality of phase windings, an output terminal connected to each phase winding so as to output excitation current to the phase winding, and controlling the output of the output terminal. a drive element having an input terminal for driving the step motor in the normal rotation; In a step motor drive device comprising an excitation phase selection circuit that outputs a control signal, the step motor is provided in the excitation phase selection circuit and is electrically connected during normal rotation drive of the step motor so as to apply a brake to normal rotation drive of the step motor. designating means for designating the input terminal corresponding to a reverse drive side phase winding different from the phase winding; and designation means connected to each of the input terminals to detect the rotational speed of the step motor and to correspond to the rotational speed. an analog brake signal generation circuit that is capable of outputting an analog brake signal; and an analog brake signal generation circuit that is connected to the input terminal and conducts the analog brake signal output from the analog brake signal generation circuit to the input terminal specified by the specification means. 1. A step motor drive device comprising a conduction means. 2. In the step motor drive device according to claim 1, the drive element is composed of a drive transistor, the input terminal corresponds to the base of the drive transistor, and the conduction means is configured to connect the drive transistor to the step motor drive device. a 3-state buffer gate connected to the base of the 3-state buffer gate, and a backflow prevention element and a resistor connected between the base of the drive transistor and the analog brake signal generation circuit, A step motor drive device comprising a gate signal generator for controlling a buffer gate.