JPS6130520B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a driving circuit for a stepping motor used particularly in a paper feeding device of a recorder.

To use the stepping motor outside the self-starting region (through region) when feeding high-speed paper in a recorder, first start it in the self-starting region, and then gradually increase the rotation control pulse to accelerate the motor. It is necessary to move to the through area while doing so. and,
After through-up in this manner, it is necessary to fix the rotation control pulse with high precision. A voltage-frequency (Vf) converter is normally used as this driving means, but in that case, it is required to have high stability against changes over temperature or time. Furthermore, there is also a known method of programming with a microprocessor, which is expensive.
In order to solve these problems, the applicant previously proposed in Utility Application No. 55-133972 a device to drive the stepping motor by using a Vf converter at startup and switching to a crystal oscillator after through-up. did. According to this invention, high rotational accuracy can be obtained even after through-up, and the rotational configuration is simple and the device can be constructed at low cost. If the frequency of the Vf converter is less than the frequency of the crystal oscillator, there is a risk that the stepping motor will stop due to imbalance. Also,
It has been found that when two unsynchronized signals are randomly switched, a high frequency momentarily occurs depending on the switching timing, which tends to cause instability such as stopping the stepping motor. Regarding this point, for example, Japanese Patent Application Laid-Open No. 74815/1983 has a phase coincidence detection circuit that compares each phase of the output pulse of a variable frequency oscillator and the output pulse of a fixed frequency oscillator, and the output of this phase coincidence detection circuit is discloses a prior art technique in which each oscillator is controlled by switching, but this technique requires a differentiating circuit and many logic elements, making the structure complex and the design troublesome, as well as being costly. There is a problem.

Therefore, an object of the present invention is to provide a circuit that has two drive means, a Vf converter and a crystal oscillator, and can extremely smoothly switch from the Vf converter to the crystal oscillator after through-up. An object of the present invention is to provide a stepping motor drive circuit with a simple configuration.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the accompanying drawings.

This drive circuit includes a Vf converter 1 and a crystal oscillator 2 as a drive source for a stepping motor (not shown). The output side of the Vf converter 1 is connected to a drive power source 5 via an integrator 3 and a start/stop switch 4, while its output side is connected to one input terminal of a NAND circuit 6 and a J.K flip-flop circuit. They are connected to the 7 CP terminals, respectively. Further, this drive circuit is provided with a voltage comparison circuit 9 that compares the input voltage V applied from the integrator 3 to the Vf converter 1 and the reference voltage Mref from the reference power supply 8. circuit 9
The output terminal of J/K flip-flop circuit 7 is
terminal and the reset _D terminal. In this case, the reference voltage Vref is set slightly higher than the predetermined through region voltage Vc required when driving the stepping motor in the through region, as shown in FIG. The voltage comparator circuit 9 goes low when the input voltage V<the reference voltage Vref.
When level “L”, input voltage > reference voltage Vref
Outputs high level "H" signals. Therefore, input voltage ≒ V near reference voltage Vref
- The output frequency of the f converter 1 is set _{to 1} , and the predetermined driving frequency corresponding to the above-mentioned through region voltage Vc is set to 1.
₂ , the relationship ₁ > ₂ is established. On the other hand, the crystal oscillator 2 is one that outputs an oscillation frequency several tens of times higher than the drive frequency ₂ in the through region. By repeating the rotation, a predetermined driving frequency ₂ is obtained. The driving frequency ₂ frequency-divided by the frequency dividing circuit 10 is applied to one input terminal of the NAND circuit 11. The Q terminal of the JK flip-flop is connected to the control terminal of the frequency divider circuit 10 and the other input terminal of the NAND circuit 11, and the terminal is connected to the other input terminal of the NAND circuit 6. Further, each output terminal of the NAND circuits 6 and 11 is connected to an OR circuit 12, and a drive signal is outputted from the OR circuit 12 to a driver circuit (not shown) of a stepping motor.

Next, the operation of this invention will be explained. When the start/stop switch 4 is turned on, the drive power supply 5 and the integrator 3 are connected, and the Vf converter 1
An input voltage V that rises based on the time constant of the integrator 3 is applied to the integrator 3. This input voltage V is compared with a reference voltage Vref in a voltage comparison circuit 9. In this case, when the input voltage V<the reference voltage Vref, the output of the voltage comparator circuit 9 is "L", so the J/K flip-flop circuit 7 does not perform inversion operation and the Q terminal is at the "H"level; is maintained at the "L" level. Therefore, the NAND circuit 11
is "closed", NAND circuit 6 is "open", and V-f
A pulse signal from the converter 1 is applied to a stepping motor driver circuit (not shown) via a NAND circuit 6 and an OR circuit 12, whereby the stepping motor is started within the self-starting region and is through-up. On the other hand, the input voltage V
increases and when the input voltage > reference voltage Vref,
The output of the voltage comparison circuit 9 becomes "H" (see FIG. 3). In that case, in this example, J.K.
After the voltage comparator circuit 9 operates as described above, the flip-flop circuit 7 receives the V applied to the CP terminal.
- It is set to perform an inversion operation at the first rising edge (trailing edge) of the pulse from the -f converter 1. Therefore, the output of the voltage comparison circuit 9 is "H"
At the first rise of the pulse from the Vf converter 1, the Q terminal and the terminal are inverted, the NAND circuit 11 becomes "open" and the NAND circuit 6 becomes "closed", and at the same time, the frequency divider circuit 10 operates. Start. As a result, the pulse signal output from the crystal oscillator 2 is frequency-divided by the frequency divider circuit 10 and outputted as a pulse signal of frequency ₂ by the NAND circuit 11 and the AND circuit 12.
is applied to the stepper motor driver circuit via.

In this way, the stepping motor is started in the self-starting region, and is driven by the high-precision crystal oscillator 2 in the through region after being through-up.According to the present invention, when switching Since the frequency ₁ of the V-f converter 1 is set higher than the frequency ₂ of the crystal oscillator outputted through the frequency dividing circuit 10, the stepping motor is driven by the inertia of the rotor including the load. The rotation is then controlled by a drive pulse outputted from the crystal oscillator 2, and there is no risk of it stopping due to malfunction, especially in the through region. It can be made smaller by using a frequency divider circuit.

In the above embodiment, after the operation of the voltage comparator circuit 9, the J.K flip-flop circuit 7 is inverted at the first rise of the pulse output from the Vf converter 1. Of course, it is also possible to reverse the pulse at the first rise of the pulse. Furthermore, although a NAND circuit is used as the gate circuit, it is not limited to this.

As is clear from the description of the embodiments described above, according to the present invention, a simple combination of commonly used circuit elements is required except that a stable DC current is required to generate the reference voltage. ,
It is easier to design and cost-effective than conventional circuits that use phase matching detection circuits, etc., and even with such a simple circuit configuration, it is possible to switch from a Vf converter to a crystal oscillator. The effects are remarkable, such as being able to do things smoothly.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment according to the present invention, Fig. 2 is a graph showing the relationship between the signal frequency applied to the stepping motor and time, and Fig. 3 is a waveform diagram of each part in Fig. 1. It is. In the figure, 1 is a Vf converter, 2 is a crystal oscillator, and 3
is an integrator, 5 is a drive power supply, 6 and 11 are NAND circuits, 7 is a JK flip-flop circuit, 8 is a reference power supply, 9 is a voltage comparison circuit, 10 is a frequency divider circuit, 12
is an OR circuit.

Claims (1)

[Claims] 1. Voltage-frequency (V-f) selectively connected to the stepping motor via switching means
It includes a converter, a crystal oscillator, and a drive power supply connected to the input side of the Vf converter via an integrator, and drives the stepping motor in an actual starting region using the output of the Vf converter. In a driving circuit for a stepping motor, which starts up, gradually increases its rotation control pulse to move into the through region, and then switches to the crystal oscillator to maintain a predetermined rotation speed, the reference power source and the integrator to the above a voltage comparison circuit that compares the input voltage to the V-f converter with the reference voltage of the reference power supply and outputs a switching signal when the input voltage becomes greater than the reference voltage; and a switching signal is output from the voltage comparison circuit. and a drive pulse switching circuit that switches to the drive pulse of the crystal oscillator when the output pulse of the Vf converter rises or falls, and the reference voltage is set by the Vf converter to the drive pulse of the crystal oscillator. The stepping motor is set to a voltage value for outputting a frequency slightly higher than the oscillation frequency, and when the drive pulse switching circuit switches from the Vf converter to the crystal oscillator, the stepping motor 1. A driving circuit for a stepping motor, wherein the stepping motor is maintained at a predetermined rotational speed by a driving pulse outputted from the crystal oscillator after undergoing an energized rotational state due to the inertia of the stepping motor.