Stepping motor drive method and system capable of stopping the rotor in a required angular position

• US 4,677,359 A
• Filed: 02/13/1986
• Issued: 06/30/1987
• Est. Priority Date: 02/15/1985
• Status: Expired due to Term

• Current Assignee: TEAC Corporation
• Original Assignee: TEAC Corporation
• Inventors: Sakaguchi, Takahiro, Tsuyuguchi, Hiroshi, Enami, Katsuya
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): BERGMANN, SAUL
• Application Number:
  US06/829,428
• Time in Patent Office: 502 Days
• Field of Search: 318/685, 318/69 G
• US Class Current: 318/696
• CPC Class Codes: H02P 8/32 Reducing overshoot or oscillation, e.g. damping

Abstract

A drive method and system are disclosed for a stepping motor typically having several sets of four phase windings on respective stator poles of annular arrangement, and a rotor having several alternating N and S poles at constant circumferential spacings. Normally, the windings are sequentially excited as by a single or two phase drive mode to cause the rotor to rotate by increments. For stopping the rotor in a required angular position, any one or two of the four phase windings are excited in a normal direction to polarize the associated stator pole or poles into one polarity to attract one of the opposite poles of the rotor. Further, the other phase windings on both sides of the noted one or two windings are excited in the reverse direction, as by the discharge of capacitors, with the consequent polarization of the associated stator poles into the opposite polarity. The stator poles thus polarized into the different polarities make possible the positive detenting of the rotor in the required angular position.

Claims

1. A method of driving a stepping motor having a plurality of windings of different phases on respective associated stator poles of annular arrangement, and a rotor having magnetic poles and rotatably disposed concentrically inwardly of the stator poles, which method comprises:

(a) sequentially exciting the windings in a prescribed drive mode to cause an incremental rotation of the rotor toward a required angular position;

(b) exciting, when the rotor is being stopped, at least one of the different phase windings which is determined by the prescribed drive mode in order to hold the rotor in the required angular position, with the result that the associated one of the stator poles is polarized into one polarity; and

(c) also exciting, at least partly concurrently with step (b), those of the different phase windings which are disposed on both sides of said one winding, in a direction opposite to that in which said one winding is excited, with the result that the associated stator poles on both sides of said one stator pole are polarized into the opposite polarity, the stator pole of the one polarity and the neighboring stator poles of the opposite polarity conjointly acting on the rotor to positively hold the same in the required angular position.

2. The stepping motor drive method of claim 1 wherein the prescribed drive mode is a single phase drive mode.

3. The stepping motor drive method of claim 1 wherein the prescribed drive mode is a two phase drive mode.

4. A method of driving a stepping motor having first, second, third and fourth phase windings on respective stator poles of annular arrangement, and a rotor having magnetic poles and rotatably disposed concentrically inwardly of the stator poles, which method comprises:

(a) sequentially exciting the four phase windings in a prescribed drive mode to cause the incremental rotation of the rotor toward a required angular position;

(b) exciting, when the rotor is being stopped, at least one of the four phase windings which is determined by the prescribed drive mode in order to hold the rotor in the required angular position, with the result that the associted one of the stator poles is polarized into one polarity; and

(c) also exciting, at least partly concurrently with step (b), those two of the four phase windings which are disposed immediately on both sides of said one winding, in a direction opposite to that in which said one winding is excited, with the result that the associated stator poles on both sides of said one stator pole are polarized into the opposite polarity, the stator pole of the one polarity and the neighboring stator poles of the opposite polarity conjointly acting on the rotor to positively hold the same in the required angular position.

5. The stepping motor drive method of claim 4 wherein all but said one of the four phase windings are excited in the opposite direction.

6. A drive system for a stepping motor of the type having a plurality of different phase windings on respective stator poles of annular arrangement, and a rotor having magnetic poles and rotatably disposed concentrically inwardly of the stator poles, the drive system comprising:

(a) power supply means connected to the windings each at a first extremity thereof;

(b) a switching element connected between a second extremity of each winding and ground;

(c) a phase control circuit for making on/off control of the switching elements in response to stepping pulses for causing the excitation of the windings in a prescribed drive mode and hence for causing the rotor to rotate incrementally to a required angular position, the phase control circuit finally causing the excitation of at least one of the windings which is determined by the prescribed drive mode, in order to hold the rotor in the required angular position, with the result that the associated one of the stator poles is polarized into one polarity; and

(d) reverse excitation means for exciting, at least partly concurrently with the final excitation of said one winding by the phase control circuit, those of the different phase windings which are disposed on both sides of said one winding, in a direction opposite to that in which said one winding is excited, with the result that the associated stator poles on both sides of said one stator pole are polarized into the opposite polarity, the stator pole of the one polarity and the neighboring stator poles of the opposite polarity conjointly acting on the rotor to positively hold the same in the required angular position.

7. The stepping motor drive system of claim 6 wherein the prescribed drive mode is a single phase drive mode.

8. The stepping motor drive system of claim 6 wherein the prescribed drive mode is a two phase drive mode.

9. A drive system for a stepping motor of the type having first, second, third and fourth phase windings on respective stator poles of annular arrangement, and a rotor having magnetic poles and rotatably disposed concentrically inwardly of the stator poles, the drive system comprising:

(a) a first supply terminal for providing a first supply voltage;

(b) a second supply terminal for providing a second supply voltage lower than the first supply voltage;

(c) power switching means for selectively connecting the first and second supply terminals to first extremities of the first to fourth phase windings;

(d) first to fourth switching elements connected respectively between second extremities of the first to fourth phase windings and ground;

(e) first to fourth capacitors connected between the second extremities of the first and second, second and third, third and fourth, and fourth and first, phase windings respectively;

(f) a phase control circuit for making on/off control of the first to fourth switching elements in response to stepping pulses for causing the excitation of the first to fourth phase windings in a prescribed drive mode and hence for causing the rotor to rotate by increments; and

(g) a power control circuit connected to the power switching means for holding the first supply terminal connected to the first to fourth phase windings when a series of stepping pulses are being supplied to the phase control circuit at a predetermined recurrence rate, and for causing the power switching means to connect the second supply terminal to the first to fourth phase windings upon termination of each series of stepping pulses.

10. The stepping motor drive system of claim 9 wherein the power switching means comprises:

(a) a transistor connected between the first supply terminal and the first extremities of the first to fourth phase windings; and

(b) a diode connected between the second supply terminal and the first extremities of the first to fourth phase windings.

11. The stepping motor drive system of claim 9 wherein the power control circuit comprises a retriggerable monostable multivibrator which remains in an unstable state for a predetermined length of time longer than the predetermined time distance between the stepping pulses.