JPS6321199Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant current chopper type stepping motor drive device.

Conventionally, the current flowing through the windings of a stepping motor is detected by the voltage generated across a detection resistor, and the winding current is kept constant by controlling this voltage so that it matches a reference voltage. A stepping motor drive device having a constant current chopper function is known.

FIG. 1 is a block diagram showing a conventional drive device.
This conventional device uses a phase switching signal 9A or 9B from a phase switching signal generation circuit 6 to determine whether or not current can flow into the winding 3A or 3B in the current flow path to each of the windings 3A and 3B constituting the stepping motor. A switching element Tr1A for determining, a switching element Tr2A for turning on/off the current flowing into the winding 3A or 3B, and a resistor R1A for taking out the detected voltage due to the current flowing into the winding 3A or 3B.
are inserted in series, and an amplifier 7A for comparing the detection voltage with a reference voltage, which will be described in detail later, and the switching element Tr2A are connected to the output side of this 7A.
This configuration includes a pulse width modulator 8A for driving. In addition, the part surrounded by the dotted line through the connection terminal of the winding 3B is the same component as the switching elements Tr2A, Tr1A, the resistor R1A, the amplifier 7A, and the pulse width modulator 8A, which are connected to the winding 3A. It is configured.

In the figure, 1 is a motor pulse supply terminal, 2
Reference numeral 4 indicates a connection terminal for a motor drive power source, 4 a motor rotation/stop signal supply terminal, 5 a stabilizing power supply connection terminal, and 6 a phase switching signal generation circuit.

Fig. 2 shows a waveform diagram to explain the operation of Fig. 1, and symbols 1, 4, and 10 are motor pulses (the pulse repetition period is large, the motor rotates at low speed, and the pulse repetition period is small, the motor rotates at high speed. (corresponding to), means rotation/stop signal and reference voltage.

Now, in FIG. 1, when motor pulse 1 is input, phase switching signal generation circuit 6 outputs phase switching signals 9A and 9B to each of the A and B phases. The switching element Tr1A is turned on and off by the phase switching signal 9A, and it is determined whether the winding 3A is excited or not.

The voltage generated when the winding current flows through the resistor R1A is compared with the reference voltage 10 by the amplifier 7A, and the pulse width modulator 8A controls the on/off of the switching element Tr2A so that the potential difference between the two is eliminated.
That is, 8A controls the drive of Tr2A. As a result, the winding current is controlled to a constant value determined by the reference voltage 10 and the resistor R1A.

Here, since the rotation/stop signal 4 has a high value (High) while the motor is rotating, the output of the inverter 11 has a low value (Low) and the switching element Tr3 is turned off, so the reference voltage 10 is It is a value obtained by dividing the voltage of the stabilized power supply 5 by the resistors R2 and R3. When the motor is stopped, the rotation/stop signal 4 has a low value, so the output of the inverter 11 is high and the switching element Tr3 is turned on.If the on-resistance of Tr3 is ignored, the reference voltage 10 is the voltage of the stabilized power supply 5. Since the voltage is divided by the parallel resistance of resistors R3 and R4 and the resistor R2, the winding current flowing through the winding of the stepping motor decreases.

However, when using this circuit to drive a motor at a wide range of speeds from low to high speeds, the motor torque decreases as the speed increases, so the reference voltage during rotation is set high to ensure the necessary torque at the maximum speed used. There is a need to. For this reason, more power than necessary is consumed during low-speed rotation, and the large torque increases noise and vibration. In addition, during high-speed rotation, the pull-out torque becomes larger than the pull-in torque, but since the reference voltage is the same both at startup and after startup, there is a drawback that power consumption, noise, and vibration increase during rotation.

This invention solves these drawbacks by rotating and
By using the stop signal and the high-speed/low-speed switching signal to switch the reference voltage to a necessary and sufficient value when starting high-speed rotation, during high-speed rotation, and during low-speed rotation, the stepping motor can be operated with low noise and at a wide range of speeds. The present invention provides a stepping motor drive device that can be driven with low vibration and low power consumption, and will be explained in detail below with reference to the drawings.

FIG. 3 is a block diagram showing an embodiment of the device of the present invention, and the signals corresponding to those in FIG. 1 are the same.
The reference voltage generation source referred to in the present invention is at least three parts of the reference voltage 10 in the waveform diagram of FIG.
A plurality of resistors R2, R3, R are connected to obtain a first reference voltage, a second reference voltage, and a third reference voltage in stages.
4 and R5 and switching elements Tr3 and Tr4 for switching the connection state of the plurality of resistors, and depending on the third reference voltage, the winding corresponding to at least low speed rotation of the stepping motor. Depending on the current and first reference voltage, a winding current necessary to start high-speed rotation, and depending on a second reference voltage, a winding current sufficient to continue the high-speed rotation is supplied to the winding 3A or 3B, respectively. It has certain characteristics.

In FIG. 3, 12 is a supply terminal for a high-speed/low-speed switching signal that becomes high when the speed is high;
13 is an AND gate, 14 is a monostable multivibrator, and 15 is a NAND gate.

First, before going into the explanation of the operation, in order to help understand the operation, we will explain the supply terminals 1, 4, and 4 of the motor pulse, motor rotation/stop signal (recording/stop signal), and high-speed/low-speed switching signal, respectively. The structure of the front stage connected to 12 is shown in FIG. 4, which is a block diagram for explaining the present invention. In the block diagram of FIG. 4, the control circuit 17 controls the programmable counter 1 according to the speed setting of the operation panel 16.
Outputs a count value of 8. As shown in the waveform diagram of FIG. 5, the programmable counter 18 divides the clock signal by the count value while the rotation/stop signal (record/stop signal) at the supply terminal 4 shows a high value. Output motor pulses to supply terminal 1.

The motor pulse supplied to the motor pulse supply terminal 1 and the phase switching signals 9A, 9B have a relationship shown in the waveform diagram of FIG. 6. That is, the phase switching signal generation circuit 6 (which exhibits the function of a distribution circuit)
Each time a motor pulse is input to the supply terminal 1, the phase switching signals 9A and 9B are switched to control which phase winding (3A or 3B) of the stepping motor is excited. When the phase switching signal 9A has a high value (High), the winding 3A is excited, and when the phase switching signal 9B has a high value, the winding 3B is excited.

The operation of the embodiment shown in FIG. 3 will be explained.

In this embodiment, switching elements Tr3 and
Since a transistor is used as Tr4, the operation of FIG. 3 will be explained below using the operation function of the transistor as an example.

FIG. 7 is a waveform diagram for explaining the operation.

First, while the stepping motor is stopped, the rotation and
Since the stop signal 4 has a low value (Low), both transistors Tr3 and Tr4 are turned on, and Tr
If the on-resistance of Tr 3 and Tr 4 is ignored, the reference voltage is 1.
0 is a value obtained by dividing the voltage of the stabilized power supply 5 by the parallel resistances of resistors R3, R4, and R5 and the resistor R2, and is the lowest reference voltage (corresponding to the third reference voltage). That is, as shown in FIG. 7, while motor pulses are not being supplied to the supply terminal 1,
The aforementioned third reference voltage is supplied to the amplifier 7A as the reference voltage 10. Next, when the motor rotates at a low speed, that is, when the repetition period of motor pulses is large, the high-speed/low-speed switching signal at the supply terminal 12 is a low value (Low), so transistors Tr3 and Tr4 are turned on, and the reference voltage is set to the third This is the reference voltage and is the same as when stopped. When rotating the motor at high speed from a stopped state, the high-speed/low-speed switching signal at the supply terminal 12 is in a high value (High) state, and the rotation/stop signal at the supply terminal 4 switches from a low value to a high value. The output of the gate 13 switches from a low value to a high value, and the output of the monostable multivibrator 14 has a high value for a certain period of time, so that the transistors Tr3 and Tr4 are turned off during this period. Therefore, the reference voltage 10 becomes a value obtained by dividing the voltage of the stabilized power supply 5 by the resistors R2 and R3, that is, the first reference voltage (FIG. 7) having the highest value at the time of starting the motor. When the output of the monostable multivibrator 14 becomes a low value, the transistor Tr4 is turned on, so the reference voltage 10 is determined by the parallel resistance of the resistors R3 and R5 and the resistor R.
2 is the value obtained by dividing the voltage of the stabilized power supply 5,
The second reference voltage is lower than that at startup. Additionally, when switching to high speed while rotating at low speed, the high speed/low speed switching signal at supply terminal 12 changes from a low value to a high value while the rotation/stop signal at supply terminal 4 is at a high value. The output of the gate 13 changes from a low value to a high value, and after reaching the first reference voltage, which is a high reference voltage, for a certain period of time, similar to when starting rotation at high speed from a stopped state, the second reference voltage, which is a low reference voltage, changes from a low value to a high value. Switch to .

As a result, the winding current is minimized by the third reference voltage when the stepping motor is rotating at low speeds and stopped when the torque generated is large, and the winding current is maximized according to the first reference voltage when the stepping motor starts rotating at high speeds where the torque is small. During high-speed rotation, the winding current is intermediate between these values in accordance with the second reference voltage, so that necessary and sufficient torque can be applied to the stepping motor in each state.

FIG. 8 is a schematic configuration diagram of main parts showing another embodiment, in which a plurality of resistors are used and the reference voltage 10 is set to the first,
2 as obtained as the second and third reference voltages
At least three of the series elements are connected in series with two resistors.
The terminals are connected in parallel at each end, one end is connected to a stabilized power supply, the other end is grounded, and each intermediate connection point drives the tongue of the analog switching element 19. It is something.

The tongues are connected to the first, second and third circuits by supplying the output signals obtained from the inverter 11 and the NAND gate 15, exhibiting the same function as shown in FIG. 3, to the drive winding of the relay. The winding current to the winding 3A or 3B can also be controlled in the manner shown in the waveform diagram of FIG. 7 by supplying the reference voltage 10 of FIG. 3 to the amplifier 7A of FIG.

As detailed above, according to the present invention, it is possible to provide the necessary and sufficient torque to rotate the stepping motor at low and high speeds, and therefore the winding current is also required at the start of high-speed drive. The first reference voltage is supplied to the amplifier so as to obtain a certain torque, and during steady rotation, a second reference voltage lower than the first reference voltage is obtained and the winding current is less than that of the first reference voltage. The current value and the third reference voltage are designed so that the current during low-speed rotation or stopping becomes a smaller value than when using the second reference voltage. The necessary and sufficient torque can be obtained, and the stepping motor can be driven at a wide range of speeds with low noise, low vibration, and low power consumption.
The practical effects of the device of the present invention are remarkable.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a conventional drive device, FIG. 2 is a waveform diagram for explaining its operation, FIG. 3 is a configuration diagram showing an embodiment of the device of the present invention, and FIG. FIG. 5, FIG. 6, and FIG. 7 are waveform diagrams for explaining the present invention, and FIG. 8 is a schematic configuration diagram of main parts showing another embodiment. 1...Motor pulse supply terminal, 3A, 3B...
Motor winding, 6...Phase switching signal generation circuit, 9
A, 9B...Phase switching signal, Tr1A, Tr2A...
Switching element, R1A...Detection resistor, 7A...
...Amplifier, 8A...Pulse width modulator, R2, R
3, R4 and R5...Resistors for obtaining high, medium and low reference voltages of the first, second and third stages, Tr3, Tr4...Switching for switching the connection state of the resistors element.

Claims (1)

[Scope of utility model registration request] A switching element for determining whether or not current can flow into the windings based on a phase switching signal, in a current flow path to each winding that constitutes the stepping motor;
inserting in series a switching element for turning on and off current flowing into the winding and a resistor for extracting a detected voltage due to the current flowing into the winding;
An amplifier for comparing a reference voltage from a reference voltage generation source and the detection voltage, and a pulse width modulator for driving the switching element for turning on and off on the output side of the amplifier. In the constant current chopper type stepping motor drive circuit, the reference voltage generation source generates a first reference voltage, a second reference voltage, and a second reference voltage corresponding to high, medium, and low degrees as reference voltages from the reference voltage generation source. 3
A plurality of resistors and a switching element for switching connection states of the plurality of resistors are provided to obtain a reference voltage, and depending on the third reference voltage, a winding corresponding to at least low speed rotation of the stepping motor is provided. Supplying to the windings a winding current necessary to start the high-speed rotation depending on the line current and the first reference voltage, and a winding current sufficient to continue the high-speed rotation depending on the second reference voltage. A stepping motor drive device featuring: