JPH04340359A - Stepping motor - Google Patents

Abstract

PURPOSE:To obtain a large rotary torque and facilitate precise control by a method wherein a plurality of divided magnetic poles are provided on a rotor and stator magnetic poles corresponding to them are provided. CONSTITUTION:Magnetic poles which are divided into six parts and magnetized alternately to be N and S are provided on the rotary surface of a rotor 13. A stator is composed of first and second electromagnets 11 and 12 which have respective pairs of yoke plates 14-15 and 17-18 extending from both the sides of exciting coils 16 and 19 and having a plurality of magnetic poles 14a,b-15a,b and 17a,b-18a,b. The magnetic poles 14a, 14b, 15a and 15b of the first electromagnet 11 and the magnetic poles 17a, 17b, 18a and 18b of the second electromagnet 12 are alternately provided with a pitch half the pitch of the electrodes of the rotor. By exciting the first and second electromagnet alternately, the rotor 13 is turned step by step. With this constitution, a large rotary torque can be obtained and precise control can be achieved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor, and more particularly, to a stepping motor that is installed in a camera lens barrel and used for driving the movement of the lens barrel, shuttering, and the like.

0002

2. Description of the Related Art FIG. 14 shows a conventional stepping motor. This motor has a U-shaped yoke 1 formed with an arc and an electromagnet 3 equipped with an excitation coil 2. An electromagnet 6 configured by equipping a yoke 4 with an excitation coil 5
are arranged symmetrically with the rotor 7 in between, and these electromagnets 3 and 6 form a four-pole stator.

The rotor 7 has four polarized magnet electrodes on its rotating surface, and is rotatably supported by a motor board 8 between the magnetic poles of the electromagnets 3 and 6. The motor board 8 is, for example, a donut-shaped disc provided in the lens barrel at the periphery of the lens. In this stepping motor, when the excitation coils 2 and 5 are supplied with power according to predetermined conditions and the magnetic poles of the electromagnets 3 and 6 are alternately magnetized, the rotor 7 rotates by repeating steps due to electromagnetic action. .

0004

[Problems to be Solved by the Invention] Since the above-mentioned stepping motor has a four-pole configuration, the step angle (step width)
is large and fine rotation control is not possible. It is conceivable to increase the number of polarizations of the magnet magnetic poles provided on the rotor to make the stepping pitch finer, but the electromagnets 3 and 6 are connected to the U-shaped yoke 1.
, 4, resulting in a stator with four poles, and as a result, there are magnet magnetic poles that do not affect torque, making it impossible to obtain a predetermined rotational torque.

In view of the above-mentioned circumstances, the present invention provides a stepping motor that increases rotational torque and is suitable for precision control.
The purpose is to develop data.

[0006]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a rotor in which magnetic poles are provided at predetermined pitch intervals on a rotating surface, and a rotor that faces the rotating surface of the rotor. In a stepping motor consisting of a stator having magnetic pole parts, first and second electromagnets each having a plurality of magnetic pole parts are provided on two yokes extending in parallel from both sides of an excitation coil, and the rotor - A stator is constructed by arranging a first electromagnet on one side of the rotor and a second electromagnet on the other side so as to extend substantially on both sides of the rotor, and the magnetic pole portion of the first electromagnet The present invention proposes a stepping motor characterized in that the magnetic pole portions of the second electromagnet and the magnetic pole portion of the second electromagnet are alternately arranged to face the rotating surface of the rotor at intervals of 1/2 the pitch of the rotor magnetic poles.

Further, in the present invention, the magnetic pole portion of the first electromagnet and the magnetic pole portion of the second electromagnet are arranged in two stages parallel to the rotational axis of the rotor, and the magnetic pole portion of the first electromagnet is arranged in parallel with the rotation axis of the rotor. - A stepping motor is proposed in which the magnetic pole portion of the second electromagnet is located closer to one side of the rotor and faces the rotating surface of the rotor closer to the other side.

[0008]

[Operation] The magnetic pole parts of the first and second electromagnets forming the stator are shifted by 1/2 pitch with respect to the magnetic pole pitch of the rotor, so for example, the magnetic pole part of the second electromagnet When the first electromagnet directly faces the magnetic poles of the rotor, the magnetic pole portion of the first electromagnet faces between the magnetic poles of the rotor.

Therefore, if power is supplied alternately to the first and second electromagnets, when power is supplied to the first electromagnet, the rotor is guided and moved by the magnetic poles appearing at the magnetic pole portions of the first electromagnet. As the rotor moves forward, when the magnetic poles of the first electromagnet directly face the magnetic poles of the first electromagnet, the magnetic poles of the second electromagnet become misaligned between the magnetic poles of the rotor. When power is continuously supplied, the rotor is guided by the magnetic pole portion and moves forward. Thereafter, the rotor repeats the steps and rotates each time the first and second electromagnets are alternately supplied with power.

0010

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment, and is a perspective view of a stepping motor with the rotor separated. 1st
The electromagnet 11 and the second electromagnet 12 form a stator, and a rotor 13 is rotatably supported between the magnetic poles of the electromagnets 11 and 12.

The first electromagnet 11 has upper and lower yoke plates 14 and 1 having joint parts 14c and 15c bent on the base side.
5, and an excitation coil 16 equipped at the joints 14c and 15c.
It is structured as follows. The upper and lower yoke plates 14 and 15 are elongated plate-like bodies formed into circular arcs, and extend in parallel from both sides of the excitation coil 16, and a magnetic pole is provided on the front side of the upper yoke plate 14. The parts 14a and 14b are the lower yoke plate 15.
Magnetic pole portions 15a and 15b are respectively bent on the front side. These magnetic pole parts 14a, 14b and magnetic pole parts 15a, 1
5b are in the form of strips, and protrude in directions facing each other with a space between them inside the rotor 13.

The second electromagnet 12 has the same structure as the first electromagnet 11, and includes upper and lower yoke plates 17, 18, and excitation coils 19 installed at the joints 17c, 18c of these yoke plates 17, 18. The upper and lower yoke plates 17 and 18 have magnetic pole portions 17a, 17b, 18a and 18b formed on the front side thereof.

[0013] The first electromagnet 11 and the second electromagnet 1 described above
2 is arranged symmetrically with the rotor 13 in between, so the upper yoke plates 14 and 17 are fixed to the ring plate 20, and the lower yoke plates 14 and 17 are fixed to the ring plate 20.
The ring plates 15 and 18 are fixed to the ring plate 21. In addition,
The ring plates 20 and 21 are, for example, fixed plates that are incorporated into a lens barrel of a camera.

The rotor 13 is a cylindrical body, and its rotating surface (outer circumferential surface) has six polarized magnetic poles N, S, N, S.
, N, and S appear in this order. The rotor 13 has its support shaft 13a supported by ring plates 20 and 21 so as to be rotatable between the magnetic poles of the stator. Further, a pinion 22 is fixed to the support shaft 13a of the rotor 13, and the pinion 22 interlocks, for example, a lens drive gear or a shutter drive gear provided in a lens barrel of a camera.

The magnetic pole portion 14a of the first electromagnet 11 described above,
14b, 15a, 15b and the magnetic pole part 17 of the second electromagnet 12
a, 17b, 18a, and 18b are sequentially arranged with respect to the rotor 13 as shown in FIG. That is, the magnetic pole part 17a,
A group of magnetic poles arranged clockwise in the order of 15b, 18a, 14b is arranged on one side of the rotor 13, and magnetic pole parts 18b, 14a,
A group of magnetic poles arranged clockwise in the order of 17b and 15a are arranged on the other side of the rotor 13.

FIGS. 3 and 4 show the above-mentioned stepping mode.
Figure 3 shows an example of how to assemble the ring plate 2.
0 and 21, and FIG. 4 is an exploded perspective view of the same motor. As shown, the upper yoke plates 14 and 17 of the electromagnets 11 and 12 are fixed to a ring plate 20, and the lower yoke plates 15 and 18 are fixed to a ring plate 21, respectively. after that,
The excitation coils 16, 19 are assembled by inserting the joint portions 15c, 18c of the lower yoke plates 15, 18 into the inner holes 16a, 19a of the excitation coils 16, 19.

Next, the rotor 13 is attached to the magnetic pole portion 1 by inserting the lower support shaft 13a into the shaft hole 21a of the ring plate 21.
8b, 15a, 15b, and 18a. after that,
Insert the joints 14a, 17c of the upper yoke plates 14, 17 into the inner holes 16a, 19a of the excitation coils 16, 19, and insert the upper support shaft 13a of the rotor 13 into the shaft hole 20a of the ring plate 20. In this way, the ring plates 20 and 21 are arranged oppositely and fixed. The pinion 22 is finally fixed to the support shaft 13a.

When controlling the rotation of the stepping motor described above, the pulse voltages P11, P12, . . . shown in FIG.
... to the first electromagnet 11, pulse voltages P21, P2
2... are supplied to the second electromagnet 12, and the electromagnets 11 and 12 are alternately excited.

For example, when a pulse voltage P11 is supplied to the first electromagnet 11 at time T1 in FIG. 5, its magnetic pole portions 14a, 14b, 15a, and 15b are magnetized as shown in FIG. 6(A). As a result, if the magnet magnetic poles of the rotor 13 are as shown in the figure, the rotor 13 is drawn in the direction of the arrow shown in the figure due to the repulsion and attraction of these magnetic pole parts, and ). Note that the hatched portion of the rotor 13 is used to clarify the rotational position of the rotor 13.
This is added for convenience of explanation.

Subsequently, at time T2 in FIG. 5, the supply of pulse voltage P11 is stopped, and pulse voltage P21 is switched to the second
It is supplied to the electromagnet 12. From this, the magnetic pole parts 17a, 17b, 18a, 18b of the second electromagnet 12 are shown in FIG. 6(C).
The rotor 13 is magnetized as shown in FIG. 7, and the rotor 13 is drawn in the direction of the arrow in the figure in the same manner as described above, and advances to the position shown in FIG. 7A.

Subsequently, at time T3 in FIG. 5, the supply of pulse voltage P21 is stopped, and pulse voltage P12 becomes the first
It is supplied to the electromagnet 11. In this case, pulse voltage P12
is a negative pulse, the magnetic poles appearing in the magnetic pole parts 14a, 14b, 15a, and 15b of the first electromagnet 11 are as shown in FIG.
It has reverse magnetism compared to (A). As a result, the rotor 13 is further routed in the direction of the arrow shown in the figure, as shown in FIG. 7(C).
Step forward to the position shown.

Thereafter, the rotor 13 rotates by repeating steps by alternately supplying power to the first and second electromagnets 11 and 12 in the same manner. Furthermore, if the positive and negative values of the pulse voltages supplied to the first and second electromagnets 11 and 12 are appropriately determined, the rotor 13 will rotate in the opposite direction to the above. For example, at time T1, a negative pulse voltage is applied to the first electromagnet 1, and at time T3, a positive pulse voltage is applied to the first electromagnet 1.
1.

FIG. 8 shows a stepping mode according to the second embodiment.
FIG. In this embodiment, the first electromagnet 3
Ring parts 33d, 34 are attached to the upper and lower yoke plates 33, 34 of 1.
d, and the magnetic pole parts 33a, 33b, 33c are arranged at equal intervals on the upper yoke plate 33, and the magnetic pole parts 34a, 34b, 34c
are formed on the lower yoke plate 34 at equal intervals. The second electromagnet 32 has the same configuration as the first electromagnet 31, and the upper yoke plate 35 has magnetic pole parts 35a, 35b, and 35c, and the lower yoke plate 36 has magnetic pole parts 36a, 36b, and 36c, respectively. They are formed at equal intervals. Note that an excitation coil 37 is connected to the joint portions 33e and 34e of the yoke plates 33 and 34.
Excitation coils 38 are provided at the joint portions 35e and 36e of the coils 5 and 36, respectively, as in the first embodiment.

The first and second electromagnets 31 and 32 described above are formed as stators arranged in two stages, upper and lower. That is, the magnetic pole part of the first electromagnet 31 faces the rotating surface of the rotor 13 in the upper half region, and the magnetic pole part of the second electromagnet 32 faces the rotating surface of the rotor 13.
The lower half area is arranged to face the rotating surface of.

Further, as can be seen from FIG. 9, the magnetic pole portions of the first electromagnet 31 and the magnetic pole portions of the second electromagnet are arranged to be shifted by half a pitch with respect to the magnetic poles of the rotor 13. That is, the first
When the magnetic poles of the electromagnet 31 directly face each other, the magnetic poles of the second electromagnet 32 face between the magnet magnetic poles, and conversely, when the magnetic poles of the second electromagnet 32 directly face the magnet magnetic poles, the first electromagnet The magnetic pole portions are configured to face between the magnetic poles of the magnet. The rest of the structure is the same as that of the first embodiment.

The stepping motor of the second embodiment has a first
By supplying the pulse voltage P11 (FIG. 5) to the electromagnet 31, the magnetic pole parts 33a, 33b, 33c, 34a
, 34b, and 34c are magnetized with the polarities shown in FIG. Therefore, if the magnetic poles of the rotor 13 are as shown in the figure, the rotor 13 will move in the direction of the arrow shown in the figure and rotate to the position shown in FIG. In addition, rotor 1
The diagonal lines shown in 3 are added for convenience of explanation in order to clarify the rotational position.

Subsequently, when the power supply to the first electromagnet 31 is stopped and the pulse voltage P21 (FIG. 5) is supplied to the second electromagnet 32, the magnetic pole parts 35a, 35b, 35c, 36a, 36
b and 36c are magnetized to the polarity shown in FIG. From this, the rotor 13 further advances in the direction of the arrow shown in the figure and rotates to the position shown in FIG. Thereafter, by similarly supplying power to the first and second electromagnets 31 and 32, the rotor 13 rotates by repeating steps.

Although the embodiments of the present invention have been described above, the magnetic poles of the rotor are not limited to six polarizations, but may have an even greater number of polarizations. In this case, the first
The number of magnetic poles of the second electromagnet is increased in accordance with the number of polarizations of the rotor. Furthermore, the present invention is not limited to one-phase excitation drive, but can also be configured as a stepping motor with two-phase excitation drive or one-two phase excitation drive.

[0029]

Effects of the Invention As described above, in the stepping motor according to the present invention, the rotor is provided with multi-polar magnet magnetic poles, and the stator magnetic pole portion corresponding to these magnet magnetic poles is provided, so that the rotational torque is reduced. becomes larger, and
The motor has a small structure and can be precisely controlled. Furthermore, since the first and second electromagnets forming the stator are arranged symmetrically on the left and right sides of the rotor, they can be mounted on a ring plate, etc., and can be mounted on a camera lens barrel, etc. It is the best stepping motor to incorporate.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a stepping motor according to a first embodiment of the present invention, with the rotor separated.

FIG. 2 is a simplified diagram of the stepping motor showing the positional relationship between the magnetic poles of the rotor and the magnetic poles of the stator.

FIG. 3 is an inner view of the ring plate showing the fixed state of the yoke plate.

FIG. 4 is an exploded side view of the stepping motor.

FIG. 5 is a time chart of pulse voltages supplied to the stepping motor.

FIG. 6 is an explanatory diagram showing the rotational operation of the stepping motor.

FIG. 7 is an explanatory diagram showing the rotational operation of the stepping motor.

FIG. 8 is an exploded perspective view of a stepping motor showing a second embodiment of the present invention.

FIG. 9 is a stepping motor according to a second embodiment showing the positional relationship between the magnetic poles of the rotor and the magnetic poles of the stator.
FIG.

FIG. 10 is an explanatory diagram showing the rotational operation of the stepping motor according to the second embodiment.

FIG. 11 is an explanatory diagram showing the rotational operation of the stepping motor.

FIG. 12 is an explanatory diagram showing the rotational operation of the stepping motor.

FIG. 13 is an explanatory diagram showing the rotational operation of the stepping motor.

FIG. 14 is a plan view of a stepping motor shown as a conventional example.

[Explanation of symbols]

11 First electromagnet 12 Second electromagnet 13 Rotor 14, 15 Yoke plate 14a, 14b, 15a, 15b Magnetic pole section 16 Excitation coil 17, 18 Yoke plate 17a, 17b, 18a, 18b Magnetic pole section 19 Excitation coil 31 First electromagnet 32 Second electromagnet 33, 34 Yoke plates 33a, 33b, 33c, 34a, 34b, 34c
Magnetic pole parts 35, 36 Yoke plates 35a, 35b, 35c, 36a, 36b, 36c
Magnetic pole parts 37, 38 Excitation coil

Claims (2)

[Claims] Claim 1: A stepping motor comprising a rotor having magnet magnetic poles arranged at predetermined pitch intervals on a rotating surface, and a stator having magnetic poles facing the rotating surface of the rotor. The first and second yokes each have a plurality of magnetic pole parts formed on each of two yokes extending in parallel from both sides of the coil.
Electromagnets are provided, a first electromagnet is disposed on one side of the rotor, and a second electromagnet is disposed on the other side so as to extend substantially on both sides of the rotor, and a stator is constructed. 1. A stepping motor characterized in that the magnetic pole portions of the first electromagnet and the magnetic pole portions of the second electromagnet are alternately arranged to face a rotor rotating surface at an interval of 1/2 of the rotor magnetic pole pitch. [Claim 2] The magnetic pole portion of the first electromagnet is placed close to one side of the rotor parallel to the rotation axis of the rotor, and the magnetic pole portion of the second electromagnet is placed close to the other side facing the rotating surface of the rotor. With,
2. A stepping motor according to claim 1, wherein the magnetic pole portions of each of these electromagnets are shifted by 1/2 pitch relative to the magnetic pole pitch of the rotor.