JPS63316698A - Driving device for stepping motor - Google Patents

Abstract

PURPOSE:To rotate a stepping motor with quicker rotational frequency, by applying the driving pulse of proper frequency with proper voltage according to the sorts of feed power sources. CONSTITUTION:By a detecting circuit 8, it is discriminated that a battery is connected to the connecting section 4 of a power source, and signal is fed to a main circuit section 1. By the main circuit section 1, the first pulse train of first voltage is applied to a stepping motor 6. By the detecting circuit 8, it is discriminated that an AC power source is connected to the connecting section 4 of the power source, and signal is fed to the main circuit section 1. The main circuit 1 has second voltage higher than the first voltage, and a second pulse train shorter than the first pulse train in period is applied to the stepping motor 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used in electronic equipment such as electronic typewriters, and includes a battery and an alternating current power source (hereinafter abbreviated as AC power source).

This invention relates to a stepping motor drive device that drives a stepping motor using either one of the two power supplies.

2. Description of the Related Art Conventionally, stepping motors have been used as drive sources for driving the carriage and paper feed of electronic typewriters. A stepping motor drive device that drives the stepping motor is configured to drive the stepping motor at an optimal drive voltage and optimal frequency determined based on torque characteristics specific to the stepping motor.

A conventional stepping motor drive device will be explained below.

Fig. 2 is a circuit diagram of a conventional stepping motor drive device, in which 1 indicates a microprocessor (not shown), peripheral equipment (not shown), and memory (not shown). ), 2 is a control transistor to which a voltage of v2 [V] is applied, 3 is a resistor, and 4 is connected to a battery (not shown in the figure) or an AC power source. power connection,
5 is a power supply circuit unit that converts the supplied voltage into an appropriate voltage; 6 is a stepping motor to which a voltage of V2 [vl is applied when the control transistor 2 is turned on; 7 is a main circuit unit 1
Stepping motor 6 according to the excitation signal supplied by
This is a driver that sequentially excites each excitation phase. Note that the resistor 3 is provided to allow a hold current to flow through the stepping motor 6 when the stepping motor 6 is held.

The operation of the conventional stepping motor drive device configured as described above will be described below.

First, the rotation of the stepping motor 6 will be explained.

When the main circuit section 1 sends a signal to make the control transistor 2 conductive, the control transistor 2 becomes conductive and supplies the stepping motor 6 with a voltage of V2 [V]. Main circuit section 1 sends an excitation signal to driver 7 in parallel with sending a signal to control transistor 2 . In response to this excitation signal, the driver 7 sequentially switches and excites each excitation phase of the stepping motor 6 to rotate the stepping motor 6.

Next, the halt state of the stepping motor 6 will be explained.

If the resistance value of the resistor 3 is R3, and the resistance value of the winding of the stepping motor 6 is Rm, then the main circuit section 1 and the transistor 2
In a state where a signal is being sent to turn off the stepping motor 6, a voltage of V2/(R3+Rm) is applied to the stepping motor 6. In this state, by supplying an excitation signal to the driver 7 from the main circuit section 1 so as not to change the excitation phase of the stepping motor 6, the stepping motor 6 is bolded at a lower voltage than when rotating.

Problems to be Solved by the Invention Generally, in electronic devices, stepping motors are often configured to be driven at several speeds. However, in the conventional configuration described above, when using a battery, if you try to increase the frequency of the drive pulse (and increase the number of rotations of the stepping motor by 60 degrees), the drive current will be insufficient because it is difficult to increase the supply voltage, resulting in tax adjustments. This can cause problems such as a significant reduction in battery life, so it is necessary to set the frequency of the drive pulse according to when using a battery. The problem is that even though current can flow, the stepping motor can only be rotated at a slow speed.

Means for Solving the Problems The present invention provides a detection means for detecting whether the supplied power source is a battery or an AC power source, and applying a first pulse train of a first voltage to the stepping motor when the battery is connected;
If an AC power source is connected, the second voltage is higher than the first voltage.
The stepping motor is equipped with a control means for applying to the stepping motor a second pulse train having a voltage of 1 and a period shorter than that of the first pulse train.

Operation With the above configuration, it is possible to apply a drive pulse of an appropriate voltage and an appropriate frequency depending on the type of power supply.

Embodiment FIG. 1 is a circuit diagram of a stepping motor drive device according to an embodiment of the present invention, in which 1 is a main circuit section, 2 is a control transistor, 3 is a resistor, 4 is a power supply connection section, and 5 is a power supply circuit section. , 6 is a stepping motor, 7 is a driver,
Since these are similar to those in the conventional example, the same numbers are given to them, and the explanation will be omitted. 8 is a detection circuit for detecting whether the power supply connected to the power supply connection part 4 is a battery or an AC power supply; 9 is a detection circuit for detecting whether the power supply connected to the power supply connection part 4 is connected to an AC power supply;
When the stepping motor 6 is rotated at a speed higher than the normal rotation speed, it becomes conductive, and the control transistor 10 that applies V3 [vl, which is a voltage higher than V2 [vl] to the stepping motor 6, and the control transistor 9 are in a disconnected state. A resistor 11 is a diode for supplying current to the stepping motor 6 when the control transistor 9 is in a disconnected state.

The operation of the stepping motor drive device of this embodiment configured as described above will be explained below.

First, the case where a battery is used as the power supply will be explained.

The resistance value of resistor 10 is R10, the resistance value of resistor 3 is R3, the resistance value of the stepping motor winding is Rm1, diode 1
Let the amount of voltage drop in the forward direction of 1 be Vf.

First, the detection circuit 8 determines that the battery is connected to the power supply connection section 4 and sends a signal to the main circuit section 1. The main circuit 1 always keeps the control transistor 9 in a disconnected state based on the signal sent from the detection circuit 8. When rotating the stepping motor 6, the main circuit section 1 connects the control transistor 2, the collector-emitter of the control transistor 2 becomes conductive, and the stepping motor 6 has the following condition: Rm/(R10+Rm)xV3>V2 -Vf is R
m/ (R10+Rm)XV3 [vl drive voltage is applied, Rm/ (RIO-1-Rm)xV3<V2-Vf(7
), a driving voltage of V2-Vf[vl is applied. The main circuit section 1 connects the transistor 2 and sends an excitation signal to the driver 7. The driver 7 rotates the stepping motor 6 by sequentially switching and exciting each excitation phase of the stepping motor 6 according to this signal.

Next, a case where the supplied power is an AC power will be explained.

First, the detection circuit 8 determines that an AC power source is connected to the power supply connection section 4, and sends a signal to the main circuit section 1. The main circuit 1 connects the control transistor 9 based on the signal sent from the detection circuit 8. Furthermore, the main circuit section 1 also connects the control transistor 2, and the stepping motor 6
A driving voltage of v3[vl is applied to. After the main circuit section 1 connects the control transistors 2 and 9, it sends an excitation signal with a higher frequency to the driver 7.

-ρ- The driver 7 uses the excitation signal from the main circuit section 1 to rotate the stepping motor 6 at a faster speed than when using the battery.

As is clear from the above description, according to this embodiment, when an AC power source is connected, compared to when using a battery, a higher drive voltage and higher frequency drive pulse is applied, thereby stepping at a faster rotation speed. By rotating the motor, the stepping motor can be used effectively.

Effects of the Invention The present invention includes a detection means for detecting whether the supplied power source is a battery or an AC power source, and when the battery is connected, applies a first pulse train of a first voltage to the stepping motor;
If an AC power source is connected, the second voltage is higher than the first voltage.
The motor is equipped with a control means for applying a second pulse train having a voltage of By rotating the stepping motor at a faster rotation speed, the stepping motor can be used more effectively.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a stepping motor driving device according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional stepping motor driving device. DESCRIPTION OF SYMBOLS 1... Main circuit part, 2... Control transistor, 3...
...Resistor, 4...Power supply connection part, 5...Power supply circuit part,
6...Stepping motor, 7...Driver, 8
...Detection circuit, 9...Control transistor, 10.
...Resistance, 11...Diode.

Claims (1)

[Claims] a detection means for detecting whether the power supply is a battery or an AC power supply; and when the detection means detects that the power supply is a battery, a first pulse train of a first voltage is applied to the stepping motor; control means for applying a second pulse train having a second voltage higher than the first voltage and having a shorter period than the first pulse train to the stepping motor when the detection means detects that the stepping motor is a power source; A stepping motor drive device characterized by: