JPH0487599A - Holding circuit for stepping motor - Google Patents

Abstract

PURPOSE:To eliminate wasteful consumption of energy during holding by providing a switch to be closed in a holding state to circulate a current in a coil by a counterelectromotive force generated by the rotation of a shaft. CONSTITUTION:Signals COMMON A, COMMON B are set to a low level in a holding state, transistors Q5, Q6 are turned OFF, and switches SW1, SW2 are closed. Since a stepping motor 1 is connected to a power source only through the transistors Q5, Q6, an external current is not fed to the motor 1 by the OFF of the transistors Q5, Q6. However, when the shaft of the motor 1 is applied externally by a force to be rotated, counterelectromotive forces are generated in the coils 2-5 of the motor, and currents are circulated through the coils via the switches SW1, SW2. When the currents flows to the coils 2-5, a magnetic field is generated at the periphery of the coil, and the shaft of the motor 1 is strongly held.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hold circuit for a stepping motor.

[Conventional technology]

FIG. 2 is a circuit diagram showing a hold circuit and a drive circuit of a conventional stepping motor. stepping motor 1
One end of each of the coils 2 to 5 is connected to a transistor Q1 to Q.
The other end of each of the coils 2.3 is connected to the power supply via a transistor Q5, and the other end of each of the coils 4.5 is connected to the power supply via a transistor Q6. Further, the other ends of each of the coils 2.3 are connected to the power supply via a reverse current blocking diode DI and a current limiting resistor rl, and the other ends of each of the coils 4.5 are connected to a power source via a reverse current blocking diode D2 and a current limiting resistor r2. It is connected.

Control signals A, λ-, B, and f are applied to the bases of transistors Q1 to Q4, respectively, and control signals A, λ-, B, and f are applied to the bases of transistors Q5. Qb
Each base has a control signal C0MM0N A, C
0MMONB is applied.

FIG. 3 shows control signals A and A for the driving state (period D in FIG. 3) and hold state (period H) of the stepping motor 2.
, B, f, indicates the state of C0MM0N A, C0MM0N B. In the driving state, the signal C0MM0N A, C
0MM0N B is set to high level, signals A, B, λ-1
The coils 2.4.3.5 are sequentially energized as f is sequentially increased to a high level. In the hold state, the signal C0MM0N A,
COMMONB goes low and transistors Q5.
Q6 is turned off and no current is supplied to the stepping motor l through transistors Q5 and Q6. but,
In Figure 3, the signal λ-2W is at a high level and the transistor Q2
．． Q4 is on, current limiting resistor r1 or r2. A hold current flows into the stepping motor 1 through the reverse current blocking diode D1 or C2.

[Problem to be solved by the invention]

In the conventional stepping motor described above, a hold current is passed through the coil of the stepping motor in the hold state, and energy is consumed during the hold state. Furthermore, it was necessary to connect a circuit such as a resistor or diode to limit the hold current.

The problem to be solved by the invention, in other words, the object of the present invention is to improve the above-mentioned drawbacks, and to create a magnetic field around the coil of a stepping motor in a hold state without supplying an external current to the coil. An object of the present invention is to provide a holding circuit for a stepping motor that generates a magnetic field by causing a current generated by a back electromotive force to flow through a switch.

[Means to solve the problem]

The hold circuit of the stepping motor of the present invention includes a switch that is turned on in the hold state and circulates current in the coil by a back electromotive force generated by rotation of the shaft.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention. The difference from the conventional circuit shown in FIG. 2 is that one end of each of coils 2 and 3 is connected by switch SW1, and one end of each of coils 4 and 5 is connected by switch SW2, and the resistance shown in FIG. This is because rl, r2 and diodes Di and D2 are removed.

In the hold state, the signals C0MM0N A, C0MM0
N B is set to low level, transistor Q s +Q6
Turn off the switch and turn on the switches swi and sw2. In FIG. 1, transistors Q s and Q b
The stepping motor 1 is connected to the power supply only through the transistors Q 5 , Q r.

By turning off, no current flows into the stepping motor 1 from the outside.

However, when an attempt is made to rotate the shaft of the stepping motor 1 by applying an external force, a back electromotive force is generated in the coils 2 to 5 of the motor, and current flows through the coils through the switches SWI and SW2, respectively. When current flows through the coils 2 to 5, a magnetic field is generated around the coils, and the shaft of the motor 1 is strongly held.

In addition, when driving motor 1, switch SWI.

Turn off SW2.

〔Effect of the invention〕

As explained above, the present invention eliminates the need for a hold current to flow through the stepping motor by providing a switch that circulates current through the coil using the back electromotive force generated by the rotation of the shaft, and current limiting resistors, diodes, etc. can be removed from the circuit. , has the effect of not wasting energy while holding.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 and FIG.
The figures each show a hold circuit and a drive circuit of a conventional stepping motor. l...Stepping motor, 2-5...Coil, Q
! ~Q6...transistor, rl, r2...current limiting resistor, Dl, C2...diode.

Claims (1)

[Claims] A hold circuit for a stepping motor, characterized in that it is equipped with a switch that is turned on in a hold state and circulates current in a coil by a back electromotive force generated by rotation of a shaft.