JPH022400B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stepping motor drive device used in a radial direction feeding mechanism of a head of a disk drive device, and more particularly, The present invention relates to a drive device that can accurately set the stop position of a rotor.

[Conventional technology]

The use of stepping motors to advance the head in the radial direction of a disk in a magnetic disk drive is well known. When a stepping motor is used in the head feeding mechanism in this way,
A desired head position can be obtained relatively accurately and easily.

[Problem that the invention seeks to solve]

By the way, when the load on the stepping motor is small, the position of the magnetic poles of the rotor can be relatively precisely matched with the magnetic poles of the stator, regardless of the difference in the rotation direction. However, as the load increases, the pulling torque of the rotor's magnetic poles by the stator's magnetic poles becomes insufficient, making it difficult to always align the centers of the magnetic poles of the stator and rotor. Variations occur. In particular, if the rotor rotates in a different direction, the deviation (hysteresis) in the stopping angle position becomes large. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a stepping motor drive device that can reduce fluctuations in the stopping angle position of the rotor.

[Means for solving problems]

To achieve the above objects, the present invention comprises a stator and a rotor, and the stator has first, second, and third and fourth phase windings, the other end of the first phase winding and the other end of the third phase winding are connected, and the other end of the second phase winding and the fourth phase winding are connected; The driving device for a stepping motor has first and second power terminals connected to both ends of a DC power supply, and one end of the third phase winding and the third phase winding. a first switch element connected between one end of the fourth phase winding and the second power supply terminal; a second switch element connected between one end of the fourth phase winding and the second power supply terminal; a third switch element connected between one end of the phase winding and the second power supply terminal; and a fourth switch element connected between one end of the second phase winding and the second power supply terminal. a fifth switch element connected between the first power supply terminal and one end of the first phase winding; a fifth switch element connected between the first power supply terminal and one end of the second phase winding; a sixth switch element connected between the first power supply terminal and one end of the third phase winding; a seventh switch element connected between the first power supply terminal and one end of the third phase winding; Fourth
An eighth switch element connected between one end of the phase winding and the first, second, third, and fourth switch elements are controlled on/off by a two-phase excitation method, and the fifth , a control circuit that operates the sixth, seventh, and eighth switch elements in correspondence with the first, second, third, and fourth switch elements; and a resistor connected substantially in series with the other phase winding such that the value of the current flowing through one of the two phase windings is somewhat smaller than the value of the current flowing through the other phase winding. The present invention relates to a stepping motor driving device characterized by the following.

In addition, to show the correspondence between the above invention and the embodiment, the first power supply terminal is the DC power supply terminal 13 of the embodiment.
The second power supply terminal is the ground of the embodiment, that is, the common line 14 of the power supply, and the first to eighth switch elements are the first to eighth transistors of the embodiment.
_Q1 to _Q8 .

[Effect]

The resistor in the above invention makes the current in the winding of one phase somewhat smaller than the current in the winding of the other phase when excitation current is passed through the windings of two phases in a two-phase excitation system. As a result, the rotor is not positioned between the two windings, but is positioned slightly off-center. In this way, when the rotor assumes a biased position,
The rotor responds well to the magnetic field on the stator side. Therefore, variations in the stopping position of the rotor are reduced.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

The magnetic disk drive device according to the embodiment of the present invention shown in FIG. 1 is constructed so that a disk 1 is rotated by a motor 2 and data is converted by a magnetic head 3. A carriage 4 to which a magnetic head 3 is attached is guided by a guide rod 5 and is movable in the radial direction of the disk 1. A lead screw 6 moves the carriage 4 in accordance with the rotation angle of the stepping motor 7.
The stepping motor 7 is a permanent magnet type (PM type).
Therefore, a large number of poles 8 arranged at equal angular intervals
A stator 10 includes a stator core 9 having a stator core 9 and first, second, third, and fourth phase windings A, B, C, and D wound around poles 8 and arranged at equal angular intervals. The rotor 12 is made of a permanent magnet having a plurality of magnetic poles 11. The first to fourth phase windings A to D are divided and repeatedly wound around a plurality of poles 8 . The magnetic poles 11 of the rotor 12 include first to fourth phase windings A to D.
They are arranged so that one N pole and one S pole are located in the unit array section of . Therefore, when the N pole of the rotor 12 is opposed to the first phase winding A, the S pole of the rotor 12 is opposed to the third phase winding C. Note that in this embodiment, the first
The stepping motor 7 and the head 3 are associated in such a way that there are tracks of the disk 1 corresponding to the poles 8 of the phase and third phase windings A, C. In short, it is configured to advance one track in two steps.

FIG. 2 shows the first step motor 7 of FIG. 1.
~The electrical connections of the fourth phase windings A to D and their drive circuits are shown. The first to fourth phase windings A to D are connected to first to eighth transistors _Q1 , which function as switch elements.
Through Q ₂ , Q ₃ , Q ₄ , Q ₅ , Q ₆ , Q ₇ , Q ₈ , a DC power terminal 13 as a first power terminal and a ground, that is, a common power line 14 as a second power terminal, are connected. is placed between. One end of each winding A to D is a positive electrode, as indicated by a black circle. The other end of the first phase winding A and the other end of the third phase winding C are connected to each other, and the other end of the second phase winding B and the other end of the fourth phase winding D are also connected to each other. has been done. That is, the first phase winding A and the third phase winding C have opposite polarities and are connected in series, and the second phase winding B and the fourth phase winding D also have opposite polarities. connected in series with each other.

In addition to the first to fourth transistors Q ₁ to _{Q 4} that respond to the first to fourth phase drive signals, the fifth to fourth transistors that respond to inverted signals of the first to fourth phase drive signals are provided.
Eighth transistors Q ₅ -Q ₈ are also provided.
One ends of the first to fourth phase windings A to D are connected to a power supply terminal 13 via respective transistors Q ₅ to Q ₈ . The other end of the first phase winding A is connected to the third phase winding C and the first
The other end of the second phase winding _B is connected to the common line 14 through the fourth phase winding D and the second transistor _Q2 .
4, the other end of the third phase winding C is connected to the common line 14 via the first phase winding A and the third transistor _Q3, and the other end of the fourth phase winding D is connected to the common line 14 through the first phase winding A and the third transistor Q3. It is connected to the common line 14 via a two-phase winding B and a fourth transistor _Q4 .

The first to fourth phase drive lines _P1 to _P4 derived from the control circuit 15 are first to fourth transistors.
It is directly connected to the base of Q ₁ ~ _{Q 4} , and
It is connected to the bases of the fifth to eighth transistors _Q5 to _Q8 via NOT circuits _N1 to _N4 .

A resistor 19 connected between the DC power supply terminal 13 and the sixth and eighth transistors Q ₆ and Q ₈ is connected to the second
and the second transistor when the sixth transistors Q ₂ and Q ₆ are turned on.
The current flowing through the phase winding B is limited by about 3 to 20%, and the current flowing through the fourth phase winding D when the fourth and eighth transistors Q ₄ and Q ₈ are turned on is similarly limited.

Note that the first to fourth phase windings A to D are divided and wound around a plurality of poles 8 in FIG. 1. Of course,
When the stator 10 has a four-pole configuration, there is no need to divide the windings A to D.

Next, the operation of the stepping motor 7 will be explained with reference to FIGS. 3 and 4. If the stepping motor shown in FIG. 2 is driven by the two-phase excitation method and the stepping motor 7 is rotated clockwise, in response to the step pulse shown in FIG. 3A,
The first to eighth transistors _Q1 to _Q8 operate on and off. That is, during the period t ₁ to _{t 2} , the first, fifth, fourth, and eighth transistors Q ₁ , Q ₅ , Q ₄ , and Q ₈ are turned on, and the first phase winding is turned on as shown in FIG. 3B. A high level current in the positive direction flows in the line A, and a low level current in the positive direction flows in the fourth phase winding D as shown in FIG. 3E. During the period _t2 to _t3 , the first, fifth, second, and sixth transistors _Q1 , _Q5 , _Q2 , and _Q6 are turned on, and the first phase winding is turned on as shown in FIG. 3B. A high level current in the positive direction flows through A, and a low level current in the positive direction flows through the second phase winding B. During the period _t3 to _t4 , the third, seventh, second and sixth transistors _Q3 ,
Q ₇ , Q ₂ , and Q ₆ are turned on, and a high level current in the positive direction flows through the third phase winding C, and a low level current in the positive direction flows through the second phase winding B. During the period _t4 to _t5 , the third, seventh, fourth and eighth transistors _Q3 ,
Q ₇ , Q ₄ , and Q ₈ are turned on, and a high level current in the positive direction flows through the third phase winding C, and a low level current in the positive direction flows through the fourth phase winding D. In the stop period after _t5 , the same excitation current as in the period _t1 to _t2 flows. During this stop control period of the rotor 12,
An excitation current of a first level flows through the first phase winding A,
When the excitation current of the second level limited by the resistor 19 flows through the fourth phase winding D, the pole 8b of the first phase winding A shown in FIG. 4 becomes a relatively strong S pole, and the fourth phase winding Pole 8a of line D becomes a relatively weak south pole. Therefore,
Between the poles 8a and 8b and the central axis 12 of the rotor 12
The magnetic flux distribution is not symmetrical with respect to the center line 17 connecting the rotor 12
The rotor stops with the center line 18 of the N pole 11 being biased to the right side of the center line 17.

Although the case where the rotor 12 rotates clockwise has been described above, the same operation occurs when the rotor 12 rotates counterclockwise.

If the current and magnetic field are determined so that the center line 18 of the north pole 11 of the rotor 12 is slightly shifted from the center line 17 as shown in FIG. dead zone) becomes smaller. Therefore, the deviation (hysteresis) in the stop position between when the rotor 12 is driven clockwise and when it is driven counterclockwise is also extremely small.

Note that even when the stop control period starts from time t ₁ , t ₂ , or t ₃ , the same operation as at time t ₀ or t ₄ occurs.

The present invention is not limited to the above-described embodiments, and, for example, the following modifications are possible.

(A) Instead of the permanent magnet stepping motor shown in principle in FIG. 1, a hybrid stepping motor shown in FIGS. 5 and 6 may be used. A rotor 31 of this hybrid stepping motor includes a permanent magnet 32 and a layered steel plate 3.
3 and has an uneven surface. Furthermore, the surface of the poles of the stator 34 is also uneven, so that a small step angle can be obtained. In addition, the windings are provided in two layers, with poles 1, 2, 3,
For 4, 5, 6, 7, 8, 1st to 4th on the outside
The phase windings are arranged in the order of A, B, C, D, A, B, C, D, and the inner windings are C, D, A, B, C, D,
They are arranged in the order of A and B.

(B) A second level of current is applied to the first and third phase windings A and C, and the first level of current is applied to the second and fourth phase windings B and D.
It may be possible to flow a current at a level of .

〔Effect of the invention〕

As is clear from the above, by biasing the magnetic flux distribution on the stator side and biasing the angular position of the magnetic poles of the rotor, it is possible to obtain an accurate stopping angular position of the rotor.

[Brief explanation of drawings]

FIG. 1 is a principle diagram showing a disk drive device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a drive circuit of the embodiment, FIG. 3 is a waveform diagram of each part of FIG. 2, and FIG. FIG. 3 is a partial sectional view of the stepping motor showing the stop position of the rotor based on the control; FIG. 5 is a sectional view showing a modified example of the stepping motor;
The figure is a sectional view corresponding to the line AA in FIG. 5. 10... Stator, 11... Magnetic pole, 12... Rotor, 13... Power terminal, A... First phase winding, B...
...Second phase winding, C...Third phase winding, D...Fourth phase winding, _Q1 to _Q8 ...Transistor.

Claims (1)

[Scope of Claims] 1. Consisting of a stator and a rotor, the stator has first, second, third and fourth phases each having one end of a first polarity and the other end of a second polarity. Equipped with a winding,
The other end of the first phase winding is connected to the other end of the third phase winding, and the other end of the second phase winding is connected to the other end of the fourth phase winding. A driving device for a stepping motor, comprising: first and second power terminals connected to both ends of a DC power source; and a second power terminal connected between one end of the third phase winding and the second power terminal. a first switch element; a second switch element connected between one end of the fourth phase winding and the second power supply terminal; one end of the first phase winding and the second power supply terminal; a fourth switch element connected between one end of the second phase winding and the second power supply terminal, and the first power supply terminal. and one end of the first phase winding; and a sixth switch element connected between the first power supply terminal and one end of the second phase winding. a seventh switch element connected between the first power supply terminal and one end of the third phase winding; and a seventh switch element connected between the first power supply terminal and one end of the fourth phase winding. The connected eighth switch element and the first, second, third and fourth switch elements are controlled on and off by a two-phase excitation method, and the fifth, sixth, seventh and eighth switch elements are controlled on and off using a two-phase excitation method. a control circuit that operates the switch elements in correspondence with the first, second, third and fourth switch elements; and one of the two phase windings through which excitation current is simultaneously passed in a two-phase excitation system. and a resistor connected substantially in series with the other winding so that the value of the current flowing in the other winding is somewhat smaller than the value of the current flowing in the other winding. Drive device.