JPH04312400A - Reverse drive method for stepping motor - Google Patents

Abstract

PURPOSE:To provide a reverse drive method for a stepping motor having a low power consumption and requiring a short time until the steady state is obtained in reverse direction. CONSTITUTION:At first, a rotor is rotated forward (c) by a pulse A within the range where no forward stepping occurs; then a reverse polarity type pulse B is applied and the rotor reversed (d); in the state where the magnetic pole of the rotor exceeded the dynamic magnetic center line of the rotor, the motor is rotated by inertial force (f), (g); then, the magnetic pole of the rotor exceeds the dynamic magnetic center line and, thereafter, the consumption current of motor can be made smaller proportionally since the rotor is rotated by the inertial force; and the driving force of the rotor is already stopped before a predetermined time when the magnetic pole of the rotor reaches the steady state line, so that the converging time of the rotor to the steady state line can be shortened.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a step motor in reverse.

0002

[Prior Art] A single-phase pulse motor used in a crystal oscillation type watch, etc. consists of a rotor consisting of a permanent magnet magnetized with two radial N and S poles, and a stator having stator magnetic poles for driving this rotor. , the rotor is rotated in steps by drive pulses. Such a single-phase pulse motor is normally designed so that the rotor is rotationally driven only in the forward rotation direction.

Normally, in a pulse motor configured for forward rotation, the angle from the rotor's static stable position (static stable line) to the dynamic magnetic center position (dynamic stable line) is approximately 45 degrees in the reverse direction. It is ゜. In addition, the branching point at which the rotor's magnetic poles rotate to reach a statically stable position (hereinafter referred to as the "static neutral point") is usually approximately on the perpendicular bisector of the statically stable line. There is.

[0004] It is possible to make the single-phase pulse motor configured as described above rotate stepwise not only in the forward rotation direction but also in the reverse rotation direction by only applying a predetermined composite pulse. It is considered. By doing this, it is possible to rotate the pulse motor step by step in the reverse direction without complicating the mechanical structure of the pulse motor, which can be used for adjusting the hands of a clock, reciprocating rotation of a decorative pendulum of a clock, etc. can be used.

[0005] As this prior art, Japanese Patent Publication No. 62-431
No. 48 is known. In the same publication, a composite pulse consisting of a combination of three pulses, that is, a pulse A having a polarity opposite to that of the normal rotation pulse in the relevant step, and a pulse B following the pulse A and having the opposite polarity. , using a composite pulse that precedes pulse A and combines pulse C with the same polarity as the pulse for forward rotation in the relevant step, but with a pulse width insufficient to achieve forward rotation, in the reverse direction. A technique for rotating in steps is disclosed. According to this, first, a pulse C of a predetermined pulse width is applied within a range where the magnetic pole of the rotor does not exceed the position of the static neutral point, the rotor is rotated in the normal direction, and the return motion of the rotor is accelerated by attraction with the subsequent pulse A. , pulse B is applied at the timing when the rotor's magnetic poles reach the vicinity of the dynamic magnetic center position, and this causes the rotor to repel and further accelerate in the reverse direction, causing the rotor's magnetic poles to cross the static neutral point. , the application of pulse B ends when the static stable position is reached.

[0006] In this way, in order to rotate the rotor forward using pulse C within a range in which the rotor's magnetic pole does not exceed the static neutral point, and then apply pulse B to rotate the rotor in reverse, it is necessary to
) Pulse A can be added to the sum of the period from when the rotor starts returning to the static stable position and (2) the period from the static stable position to the dynamic magnetic center position, and if pulse C is not added. In comparison, a large reverse drive torque can be obtained.

[0007]

[Problem to be Solved by the Invention] However, the pulse B is applied until the magnetic poles of the rotor reach a static stable position from the dynamic magnetic center position, and then the rotor is stopped at the static stable position by a convergent action. Therefore, when the application of pulse B is stopped, a large inertial force is acting on the rotor. Therefore, the magnetic poles of the rotor vibrate around the statically stable position and converge to the statically stable position. This phenomenon is called rotor hunting, but there is a problem in that it takes a long time for this hunting to subside. Therefore, there is a problem in that it is inconvenient when rotating the rotor at high speed.

[0008] Furthermore, since the reverse rotation driving is performed using a composite pulse consisting of three pulses, there is a problem in that the power consumption required for driving becomes large. In particular, the pulse B applied when the rotor's magnetic poles are at the dynamic magnetic center position contributes to an increase in the rotational drive torque of the rotor because the direction in which the repulsive force from the magnetic field acts is approximately toward the center of the rotor. Therefore, the contribution of pulse B to the increase in the rotational force on the rotor was small compared to the increase in power consumption due to the application of pulse B.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to be able to reliably rotate the rotor, to shorten the time required for the magnetic poles of the rotor to converge to a statically stable position, to enable high-speed rotation, and to reduce power consumption. An object of the present invention is to provide a method for driving a small step motor in reverse.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a rotor comprising a permanent magnet magnetized to two N and S poles, and a pair of stator magnetic poles for magnetically driving the rotor. and a drive coil that excites this stator, and each time the rotor moves in the opposite direction, the polarity is the same as that of the drive pulse for forward rotation in that step, but in order to achieve the forward rotation step. A composite pulse that combines a pulse A with an insufficient pulse width and a pulse B that follows the pulse A and has the opposite polarity and is applied until the rotor rotates in reverse and reaches the dynamic stability line. A reversing drive pulse consisting of the following is applied in a predetermined cycle to reverse the rotor.

[0011]

[Operation] Pulse B can be applied within a large rotation angle until the rotor, which has advanced a predetermined amount in the forward rotation direction, reverses and reaches the dynamic magnetic center line (dynamic stability line).
The application of pulse B allows the rotor's magnetic poles to cross the static neutral point due to inertia after the rotor's magnetic poles pass the dynamic magnetic center position, and the voltage and width of pulse B Its value is set such that after passing the dynamic magnetic center position, inertia allows the rotor's magnetic poles to pass the static neutral point.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a step motor using a notched integral stator. The rotor 1 is composed of a disc-shaped permanent magnet magnetized into two poles, an N pole and an S pole. Rotor 1
assumes that counterclockwise rotation is normal rotation.

The left and right sides of the stator 2 are integrated, and a circular hole 2a into which the rotor 1 is inserted is provided in the center. Narrow width portions 2b and 2c are provided at the upper and lower sides of the stator 2 on a straight line Y extending vertically in FIG. 1 through the center of the circular hole 2a. The narrow width portions 2b and 2c have a small cross-sectional area and a large magnetic resistance. As a result, the stator 2 acts as if it were magnetically divided into left and right sides with the straight line Y as a boundary, and a pair of stator magnetic poles are formed on both sides with the hole 2a in between.

A coil core 5 is provided at the lower end of the stator 2, and a drive coil 6 is wound around the coil core 5. The drive coil 6 is provided with two drive current input terminals 6a and 6b on the left and right sides. A straight line L2 passing through the center of the circular hole 2a and extending in the left-right direction in FIG. 2 is the magnetic center line when energized. When a drive current is applied to the drive coil 6 through the input terminals 6a and 6b, it is excited through the coil core 5 so that the stator magnetic poles become N and S poles. When the stator 2 is energized, the rotor 1 has its magnetic poles aligned with the magnetic center line L.
2. Receive an upward force.

The circular hole 2a has a pair of arcuate notches 2.
d and 2e are provided. The notches 2d and 2e are provided on a line (notch center line) L3 passing through the center of the circular hole 2a, and the notch center line L3 is provided at a position of −45° counterclockwise with respect to the dynamic magnetic center line L2. There is. A substantially perpendicular bisector of the notch center line L3 becomes the static stability line L1 of the rotor 1 when no current is applied. Notch center line L3
is the branch line (static neutral line) indicating in which direction the magnetic poles of the rotor rotate to reach a statically stable position.

Hereinafter, L1 will be referred to as the "static stability line," L2 will be referred to as the "dynamic magnetic center line," and L3 will be referred to as the "static neutral line."

The step motor 11 shown in FIG. 1 is, for example, shown in FIG.
It is incorporated into a crystal oscillation clock as shown in the figure. The frequency output from the crystal oscillator 12 is divided by a frequency divider 13 and finally becomes 1 Hz, which is input to the control circuit 14. The control circuit 14 has a forward rotation pulse generation circuit and a reverse rotation pulse generation circuit (not shown), and sends a forward rotation pulse or a reverse rotation pulse to the driver 15 as a drive signal every 1 Hz. The driver 15 generates a drive current corresponding to these drive signals, and this drive current is supplied to the step motor 11. This causes the step motor 11 to rotate. Whether the control circuit 14 sends a forward rotation pulse or a reverse rotation pulse as a drive signal is determined by sending a forward/reverse switching signal 16 to the control circuit 14 . step motor 1
1 rotates the hands of the watch via a predetermined wheel train or the like.

Next, the reversal pulse and the movement of the rotor due to the reversal pulse will be explained in detail.

In FIGS. 3 and 4, as shown in FIG. 4(a), the magnetic poles of the rotor 1 are initially located on the static stability line L1 with the N pole on the upper right side and the S pole on the lower left side. do. In addition, in the pulse waveform diagram of FIG. 3, the stator is excited by a positive pulse (positive is above the reference line) so that the right side is the N pole and the left side is the S pole (state in FIG. 4(b)).
Assume that a negative pulse causes the opposite excitation.

The reverse pulse has the same polarity as the normal rotation drive pulse, but has a pulse width insufficient to achieve forward rotation, and a pulse A that follows pulse A but has the opposite polarity. , and pulse B, which is applied until the rotor rotates in reverse and reaches the dynamic stability line.

Pulse A in FIG. 3 is applied when the magnetic poles of rotor 1 are in the position shown in FIG. 4(a). Then, the rotor 1 starts rotating normally (the state shown in FIG. 4(b)). Then, when the rotor 1 rotates forward by 45° (the state shown in FIG. 4(c)), the pulse B shown in FIG. 3 is applied. Then, the polarity of the stator magnetic poles is reversed, and the rotor 1 further rotates forward by a predetermined angle due to inertia (
(see FIG. 5), and is attracted to the stator magnetic poles and rotates in the opposite direction (state of FIG. 4(d)). Even after applying pulse B in Fig. 3, the rotor 1 continues to rotate forward by a predetermined angle due to inertia, but the width and height of pulse A are adjusted so that the magnetic pole (N pole) does not exceed the static neutral line L3. Set the value. this is,
When the magnetic pole of the rotor crosses the notch static neutral line L3, a rotational moment acts on the rotor 1 in the forward rotation direction, and the rotor 1
This is to prevent the drive torque required to reverse the rotation from increasing. Since pulse B in FIG. 3 is applied when rotor 1 rotates 45° forward, the magnetic field of stator 2 generated by pulse B attracts the magnetic poles of rotor 1 almost in the radial direction of rotor 1, and therefore A large reverse rotation torque can be generated, and current consumption can be used more effectively. The pulse B is applied until the magnetic pole of the rotor 1 reaches the dynamic magnetic center line L2 (see FIG. 4).
(state e)), then stopped (state shown in Fig. 4(f))
. Then, rotor 1 continues to reverse rotation due to inertia force,
The magnetic pole crosses the static neutral line L3 toward the static stability line L1, oscillates around the static stability line L1, and stops at the static stability line L1 (state in FIG. 4(g)). From the state where rotor 1 is rotating 45 degrees in the normal rotation direction, rotor 1
Since the pulse B can be applied until the rotor 1 rotates 45 degrees in the reverse direction, it is possible to apply a very large reverse drive torque to the rotor 1 and generate a very large inertial force. The width and height of the pulse B are set so as to give the rotor 1 an inertial force that allows its magnetic pole to cross the peak of the static neutral line L3. After the magnetic pole of the rotor 1 crosses the static neutral line L3, its rotational speed rapidly decreases due to the rotational resistance of the gear train connected to the rotor 1, and even after the magnetic pole crosses the static stability line L1, the rotation speed decreases rapidly. The amount of overrun is small, and the vibrations converge rapidly (see Figure 5). Therefore, if the convergence is set to complete after 1 second, the rotational speed of the rotor 1 during the application time of pulses A and B can be made smaller, so that the convergence is The required height V2, ie, the drive voltage applied to the step motor, can be kept low, thereby reducing power consumption.

One second later, when the next signal is input to the control circuit 14 by the frequency divider 13, the reverse pulse generator generates the following signal.
A composite pulse, which is the same as the composite pulse described above but whose overall polarity is reversed, is generated, and this composite pulse further causes the rotor to rotate half a rotation in the opposite direction, and its magnetic pole stops on the next static stability line L1. When one second has elapsed, the next signal is input to the control circuit 14 by the frequency divider 13, and this composite pulse and a pulse whose polarity is inverted, that is, a pulse with the same polarity as the composite pulse explained above, are generated. Then, the rotor 1 is further rotated half a turn in the opposite direction, and by repeating this,
Rotor 1 continues to reverse rotation.

In this embodiment, it is assumed that pulse A is applied until the rotor 1 rotates 45° in the normal rotation direction.
is used to rotate the rotor 1 in the normal direction under the condition that the rotor 1 does not achieve forward rotation. If this condition is satisfied, for example, the section until the rotor 1 reaches the vicinity of the static neutral line L3 , pulse A may be applied.

Furthermore, in this embodiment, the pulse B is applied until the magnetic pole of the rotor 1 reaches the dynamic magnetic center line L2. However, when the magnetic pole of the rotor 1 reaches the vicinity of the dynamic magnetic center line L2, the pulse B of the stator is applied. Since the rotational moment of the rotor 1 received from the magnetic field becomes small, the application of the pulse B may be stopped before that.

Furthermore, in this embodiment, the composite pulse generated by the reversing pulse generator has a cycle of 1 second, but if the forward/reverse selector switch is pressed for a predetermined number of seconds, a fast reversing signal having a pre-prepared frequency is generated. vessel (not shown)
The periodic signal from
It can be used as a mechanism to quickly reset the hands of a watch. Since the present invention can shorten the convergence time of the rotor, the time required for one step advance can be shortened, and therefore a fast return mechanism having a high speed can be obtained with less electric power.

Furthermore, the present invention can be used as a drive mechanism for rotating a decorative pendulum or the like in a timepiece. Since a large reverse rotation drive torque can be obtained, objects with large rotational resistance such as decorative pendulums can be rotated in the reverse direction, and since the convergence time during reverse rotation is short, it is possible to reverse rotation at high speed, In combination with rotation and high-speed forward rotation, it is possible to obtain a large variety of movements with low power consumption.

[0028]

According to the present invention, the time required for convergence (hunting) to the static stability line during reverse rotation of the rotor is shortened, so that a fast return mechanism having a high speed can be realized.

Further, since no pulses are applied after the magnetic poles of the rotor exceed the dynamic magnetic center line, and the rotor is driven in reverse by two pulses, the power consumption required by the motor can be reduced.

Furthermore, since the convergence time of the rotor is shortened, the rotational speed of the rotor due to the pulses A and B can be reduced accordingly, and the time required for rotation can be lengthened, and the driving voltage can therefore be lowered based on this. This can reduce power consumption. These make it possible to use electric power effectively.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a step motor.

FIG. 2 is a block diagram for driving a step motor.

FIG. 3 is a waveform diagram of a composite pulse applied in the present invention.

FIG. 4 is an explanatory diagram showing the rotational state of the rotor at each position of the composite pulse in FIG. 3;

5 is a graph showing the rotation angle of the rotor versus time t when the composite pulse of FIG. 3 is applied; FIG.

[Explanation of symbols]

1 Rotor 2 Stator 6 Drive coil 11 Step motor

Claims (1)

[Claims] [Claim 1] A rotor comprising a permanent magnet magnetized to two N and S poles, a stator having a pair of stator magnetic poles for magnetically driving this rotor, and a drive coil for exciting this stator. In the method for reversing a step motor, for each step movement of the rotor in the reverse direction, a pulse A having the same polarity as the normal rotation drive pulse in the step, but having a pulse width insufficient to achieve forward rotation step. and a pulse B which is subsequent to the pulse A and has the opposite polarity and is applied until the rotor rotates in reverse and reaches the dynamic stability line. A method for reversing a step motor, characterized in that the rotor is reversed by applying voltage at a predetermined cycle.