JPH08322295A - Stepping motor driver - Google Patents

Abstract

PURPOSE: To provide a stepping motor which can stop rotation perfectly when a power supply is cut off. CONSTITUTION: If energization of a driver 20A is cut off, a stepping motor 10 is put into a non-exciting state and, at the same time, relays RL1 and RL2 are opened. As a result, closed circuits are composed of windings ϕ1 and ϕ3 and of windings ϕ2 and 44 respectively. If a force is applied to the rotary shaft of the stepping motor 10 in this state and the permanent magnets of a rotor are turned, induced currents are respectively applied to the closed circuits composed of the respective windings and magnetic forces are generated between the respective windings and the permanent magnets of the rotor so as to produce interactions between the windings and magnets, so that the rotor is braked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor drive circuit.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a drive circuit for a two-phase stepping motor. Stepping motor 1
In No. 0, the rotor is provided with a permanent magnet, and the stator is provided with a pair of windings φ1 and φ3 on the A phase side and a pair of windings φ2 and φ4 on the B phase side. Pair of windings φ1, φ3
Are excited by opposite magnetic poles, and the other pair of windings φ2
φ4 is also configured to be excited by magnetic poles opposite to each other.

One end of each winding φ1 to φ4 has a common terminal tc.
It is connected to the. The drive power supply voltage Vm for the stepping motor 10 is supplied to the common terminal tc via the transistor Q that is turned on by the power supply signal Sp.

The other end of each of the windings φ1 to φ4, that is, the terminals t1 to t4 of the pair of windings on the side separated from each other, is a driver 11-1 to 11-4 for drawing an exciting current, respectively.
(Hereinafter, it may be collectively referred to as driver unit 11) It is connected to the output side. Therefore, when the drive signals S1 to S4 of "H" level are applied to the input side of each driver, the drive power supply voltage Vm is applied to each of the windings .phi.1 to .phi.4 via the common terminal tc to supply the exciting current. . Then, the drive signals S1 to S according to a predetermined excitation method.
By supplying 4 to the driver unit 11, the stepping motor 10 is driven.

In the drive circuit 20, when the rotating shaft of the stepping motor 10 is held in a stopped state, the drive signal may be held in a predetermined state and the supply of the exciting current to the predetermined winding may be held. . Further, when the excitation current is not supplied to the stepping motor 10 due to the supply of the drive power supply voltage Vm being stopped due to the power supply of the device incorporating the drive circuit 20 being cut off or the like, the rotation shaft of the stepping motor 10 Is held only by the magnetic force acting on the stator by the magnetic poles of the permanent magnet of the rotor.

The static torque when the stepping motor is in the excited state as in the former is called holding torque, and the static torque when the stepping motor is in the non-excited state as in the latter is called detent torque. The detent torque is smaller than the holding torque.

FIG. 4 is a schematic diagram of a ball counter incorporating such a stepping motor and its drive circuit. The ball counter is a device mounted on, for example, a ball lending machine installed in a game hall. Stepping motor 1
The rotational force of the rotating shaft 10a of 0 is transmitted to the feed wheel 31 that sends the balls B through the gear train 30 including the gears 30a to 30d. That is, the gear train 30 and the feed wheel 31 constitute a driven mechanism. Stepping motor 10
When the feed wheel 31 rotates in the direction of the arrow due to the rotation of the rotary shaft 10a, the balls held in the plurality of recesses 31a provided on the outer periphery of the feed wheel 31 are sequentially discharged to the downstream side of the ball passage 32. . Since the feed wheel 31 receives the load of the plurality of balls B existing on the upstream side of the ball passage 32, the load is a force for rotating the rotating shaft 10a of the stepping motor 10 via the driven mechanism. The rotating shaft 10
acting on a.

When the ball lending machine is powered off and the ball counter is de-energized, the stepping motor 10 is de-energized. At this time, if the load applied to the rotary shaft 10a of the stepping motor 10 by the plurality of balls B existing on the upstream side of the feed wheel 31 is equal to or less than the detent torque, the rotary shaft 10a and the driven mechanism are held in a stopped state. be able to.

[0009]

However, the rotating shaft 10
When the load applied to a increases for some reason and exceeds the detent torque, the rotating shaft 10a cannot support the above load, so that the driven mechanism is rotated and the ball B is discharged downstream of the ball passage. Such inconvenience may occur. As described above, in the conventional stepping motor drive circuit, when the force applied to the rotating shaft exceeds the detent torque, which is the static torque, during non-excitation, the rotating shaft may be rotated. Therefore, in order to surely stop the rotation of the driven mechanism to which the rotational force is supplied from the stepping motor, it is necessary to provide a mechanical rotation suppressing mechanism, which causes the mechanism to become complicated and costly. There is. The present invention has been made based on such a situation, and a drive circuit for a stepping motor that does not need to be provided with a rotation suppressing mechanism in a driven mechanism in order to suppress unnecessary rotation of the rotary shaft when the stepping motor is not excited. The purpose is to provide.

[0010]

According to the present invention, in a drive circuit of a stepping motor in which a rotor is provided with a permanent magnet and a stator is provided with a winding for driving, the magnetic poles of the same phase but opposite to each other are excited. The switch means for short-circuiting is provided between the terminals of the pair of windings, which are separated from each other.

According to the present invention, the switch means is composed of a relay that is opened at the time of make and closed at the time of break, and is turned on / off in response to turning on / off the drive power supply to the stepping motor. The relay power supply voltage is supplied to the operating coil of the relay.

[0012]

When the stepping motor is in a non-excited state, when the force for rotating the rotating shaft is applied to the stepping motor and the permanent magnet of the rotor rotates while the switch means for short circuit is closed, the rotor's permanent magnet rotates. By moving the magnetic field of the permanent magnet with respect to each winding on the stator side,
Induced currents flow in the closed circuit composed of each winding. Since a pair of windings of the same phase are excited with opposite polarities,
When the above-mentioned induced current flows through each winding, a magnetic force acting on each winding is generated between each winding and the permanent magnet of the rotor, so that a braking action on the rotation of the rotor occurs. Therefore, even if a force is applied to the rotating shaft in the direction of rotating the rotating shaft, the rotation of the rotating shaft is suppressed by the braking action.

The switch means is composed of a relay which is opened at the time of make and closed at the time of break, and the relay power supply voltage which is turned on / off corresponding to the on / off of the supply of the drive power to the stepping motor is When supplied to the operation coil of the relay, the braking action of the stepping motor occurs as the driving power of the stepping motor is turned off.

[0014]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of a drive circuit for a stepping motor according to the present invention. In FIG. 1, the same or corresponding members as those in FIG. 4 showing the conventional example are designated by the same reference numerals, and the description thereof will be omitted.

First, the configuration will be described with reference to FIG. A relay RL1, which constitutes switch means for short-circuiting, is provided between the terminals t1 and t3 and between the terminals t2 and t4 on the separated sides of the pair of windings φ1 and φ3 and the windings φ2 and φ4 of the stepping motor 10, respectively. The break terminal a and the common terminal c of RL2 are connected.

One ends of the operation coils of both relays RL1 and RL2 are commonly connected to the relay power supply voltage Vcc, and the other ends are commonly connected to the output side of the driver 11-5. The break terminals a of the relays RL1 and RL2 are connected to the output sides of the drivers 11-1 and 11-2, respectively, and the make terminals b are connected to the output sides of the drivers 11-3 and 11-4, respectively. .

The drive signals S1 to S4 are input to the input sides of the drivers 11-1 to 11-4 as in the conventional circuit.
The relays RL1 and RL are connected to the input side of the driver 11-5.
A relay drive signal Sr for operating 2 is input.
The drivers 11-1 to 11-5 may be collectively referred to as a driver unit 11A.

Next, the operation will be described. When the stepping motor 10 is started, the power supply signal Sp is set to “H”, and the drive power supply voltage Vm is supplied to the common terminal tc of the windings φ1 to φ4 via the transistor Q. At the same time, by making the relay drive signal Sr "H" to make the relays RL1 and RL2 as shown by the broken lines in the figure, the output sides of the drivers 11-1 to 11-4 have windings φ1 to φ4 respectively. It is connected to terminals t1 to t4. Next, the stepping motor 10 is driven by supplying the drive signals S1 to S4 to the driver unit 11A according to a predetermined excitation method.

On the other hand, the driving stepping motor 1
When 0 is stopped, the rotation shaft is stopped by stopping the operation of supplying the drive signals S1 to S4 to the driver unit 11A. In this state, since the exciting current is supplied to any of the windings φ1 to φ4, the rotating shaft is held stationary by the holding torque.

When the power supply to the drive circuit 20A is cut off, the application of the drive power supply voltage Vm and the relay power supply voltage Vcc is stopped, so that the relays RL1 and RL2.
The current to the operating coil is stopped, the relay breaks as shown by the solid line in the figure, and the break terminal a and the common terminal c are closed. As a result, a closed circuit including the windings φ1 and φ3 is formed, and the windings φ2 and φ3 are formed.
A closed circuit composed of 4 is constructed.

Here, when a force in the direction of rotating the rotating shaft is applied to the stepping motor 10 and the permanent magnet of the rotor rotates by a certain amount, the magnetic field generated by the permanent magnet of the rotor is applied to each of the windings φ1 to φ4 on the stator side. By moving, induced voltage is generated in each of the windings φ1 to φ4. As a result, the induced currents flow in the closed circuit including the windings φ1 and φ3 and the closed circuit including the windings φ2 and φ4, respectively.

As described above, the pair of windings φ on the A phase side
1 and φ3 are excited with opposite polarities, and B
The pair of windings φ2 and φ4 on the phase side are also excited with opposite polarities. Therefore, the induced current flows through the windings φ1 to φ4, so that a magnetic force acting between each winding and the permanent magnet of the rotor is generated. As a result, a braking action on the rotation of the rotor occurs. Therefore, even if a force is applied to the rotating shaft in the direction of rotating the rotating shaft, the rotation of the rotating shaft is suppressed due to the above braking action, so that there is no need to provide a rotation suppressing mechanism in the driven mechanism, unlike the conventional case. . Therefore, unlike the conventional case, the driven mechanism can be simplified and the cost can be reduced.

When the stepping motor is in a stopped state due to the holding torque, the rotating shaft, which exceeds the holding torque, rotates around the rotating shaft. On the other hand, since the braking action according to the present invention occurs in proportion to the force applied to the rotating shaft, it is possible to suppress the rotation of the rotating shaft to the rotating shaft even if the holding torque of the stepping motor is exceeded. There is.

The braking action becomes maximum when a closed circuit is formed by windings of all phases as in this embodiment. Therefore, if the reduction of the braking action can be tolerated, the closed circuit may be formed only by the windings of some phases.

The short-circuit switch means may short-circuit the winding of the stepping motor 10. Therefore,
As shown in FIG. 2, the output side of each driver 11-1 to 11-4 is connected to each winding of the stepping motor 10, and the common terminal c of the relays RL3 and RL4 and the make contact a are connected between each winding. In addition to the connection, the make contact b may be unconnected.

The short-circuiting switch means may be a switch that is manually opened and closed instead of the relay. Further, the drive circuit of the stepping motor of the present invention may be applied to a stepping motor having windings for driving two or more phases.

[0027]

As described above in detail, according to the drive circuit of the stepping motor of the present invention, when the force in the direction of rotating the rotary shaft is applied to the stepping motor in the non-excited state, the permanent magnet of the rotor rotates. The magnetic field generated by the permanent magnets of the rotor moves with respect to each of the windings on the stator side, so that an induction current flows in each closed circuit including each winding. Since a pair of windings of the same phase are excited with polarities opposite to each other, a magnetic force acting on each other is generated between each winding and the permanent magnet of the rotor due to the induction current flowing in each winding. A braking action for the rotation of the rotor occurs.
Therefore, when a force to rotate the rotating shaft in a stopped state is applied, it is possible to suppress the unnecessary rotation of the rotating shaft by causing a braking action, and therefore a rotation suppressing mechanism for the driven mechanism. Need not be provided.

Further, the switch means is composed of a relay which is opened at the time of make and closed at the time of break, and is turned on / off in response to the on / off of the supply of the drive power to the stepping motor. Is supplied to the operating coil of the relay, the braking action of the stepping motor can be generated when the drive power of the stepping motor is turned off.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a drive circuit for a stepping motor according to the present invention.

FIG. 2 is a circuit diagram showing another embodiment.

FIG. 3 is a circuit diagram showing an example of a conventional circuit.

FIG. 4 is a schematic configuration diagram showing an example of a ball counter incorporated in a ball lending machine using a conventional circuit.

[Explanation of symbols]

 10 stepping motor φ1, φ3 A-phase winding φ2, φ4 B-phase winding t1 to t4 terminals 20A drive circuit RL1, RL2 relay (switching means for short circuit) RL3, RL4 relay (switching means for short circuit) Vcc relay Power supply voltage Vm Drive power supply voltage

Claims (2)

[Claims] 1. A drive circuit of a stepping motor in which a rotor is provided with a permanent magnet and a stator is provided with a winding for driving, and a pair of windings which have the same phase but are excited by opposite magnetic poles are separated from each other. A drive circuit for a stepping motor, characterized in that switch means for short-circuiting is provided between the terminals on the driven side. 2. A relay power supply voltage which is constituted by a relay which is opened at the time of make and closed at the time of break, and which is turned on / off in response to turning on / off of drive power supply to the stepping motor. 2. The drive circuit for the stepping motor according to claim 1, wherein is supplied to an operating coil of the relay.