JP3153341B2 - Step motor and camera using the step motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor and a camera using the step motor, and more particularly to an improvement in the structure of the step motor.

[0002]

2. Description of the Related Art It is well known that a step motor drives a shutter blade or a photographing lens of a camera (for example, Japanese Utility Model Laid-Open No. 63-113127).
No.). In the device disclosed in this publication, as shown in FIG. 28, a step motor includes a rotor 2 divided in a circumferential direction and magnetized in a radial direction, and a plurality of step motors arranged on the outer periphery of the rotor 2 so as to face the rotor 2. Stators 3 having magnetic poles of
4 and coils 5 and 6 arranged on a part of the stators 3 and 4 so as to excite the stator. The entire stepping motor has a barrel base plate 1 so as to be easily placed in the lens barrel of the camera. It is arranged in a substantially arc shape on the top.

[0003] In detail, the rotor 2 is rotatably attached to the lens barrel base plate 1 at a location 2a, and is divided into four parts in the circumferential direction as shown in FIG. It is magnetized. The stators 3, 4 have magnetic poles 3a, 3b, 4a, 4b formed so as to face the outer periphery of the rotor.
The stator motor rotates the rotor in either direction by switching the energization of the coil, and uses the rotation of the rotor to drive shutter blades (not shown) or photographing lenses (not shown).

[0004]

However, in the prior art, the magnetic poles 3a, 3b, 4
Since a and b must be arranged in a plane as shown in FIG. 28, there is a limit in shortening the dimension of the width l of the stator. There was a limit.

[0005] Looking at the conventional example from another viewpoint, there is a request as described below. For example, in particular, when driving a photographing lens using a stepping motor, the photographing lens must be stopped during the exposure operation. Generally, a method is used in which the rotor is stopped at a predetermined rotation position by cogging torque generated between the magnetized portion of the rotor and the step. However, there are only four rotational positions of the rotor that are stably held by the cogging torque, that is, the positions shown in FIGS. 28 and 29, that is, the positions taken when rotating every 90 ° (FIG. 28 shows 180 of them). °
FIG. 29 also shows two different states.
° shows two different states). In this step motor, by energizing the coils 5 and 6, the rotor can be indexed at four positions rotated by 90 degrees as shown in FIGS. However, when the power to the coil is cut off,
In this state, the cogging torque is very small, and the rotor 2 is not stably held. For this reason, for example, in order to use the positions shown in FIGS. 30 and 31 as the feeding stop position of the photographing lens, the coil is kept energized, and the electromagnetic force generated thereby causes the electromagnetic force generated in FIGS.
It was necessary to hold the rotor at the position shown in FIG.

On the other hand, when performing exposure control in operating the camera, it is necessary to energize an actuator for driving an exposure control mechanism (not shown). Considering that the power source used in the camera is a battery, it is desirable not to energize the actuator for extending the taking lens, that is, energize the coils 5 and 6 during the exposure operation.

Accordingly, a first object of the present invention is to provide a stepping motor having a structure capable of reducing the diameter of a lens barrel of a camera.

A second object of the present invention is to provide a step motor having a structure capable of reducing the diameter of a lens barrel of a camera and preventing a decrease in the generation of driving torque.

A third object of the present invention is to provide a stepping motor having a structure which can be used for extending the photographing lens without conducting electricity for extending the photographing lens even during the exposure operation in the camera.

[0010]

In order to achieve the first object described above, the present invention provides a cylindrical rotor comprising permanent magnets which are magnetized in a radial direction, and a rotor facing the outer periphery of the rotor. In a step motor having first and second stators having a plurality of arranged magnetic pole portions and coils arranged to excite each of the first and second stators, the rotor is disposed in the axial direction thereof. Two magnetized layers are formed,
Each magnetized layer has at least two magnetized portions, and the magnetic pole portions of adjacent magnetized layers are magnetized to opposite polarities, and the first
And a plurality of magnetic pole portions of each of the second stator is disposed so as to face a magnetized portion of a different magnetized layer in the axial direction of the rotor, the first and second stators by the coil for each stator The present invention employs a step motor which is specially taught to drive the rotor by sequentially switching energization of the coils of the first and second stators when energized.

According to another aspect of the present invention, there is provided a cylindrical rotor made of a permanent magnet magnetized in a radial direction;
In a step motor having first and second stators having a plurality of magnetic pole portions arranged opposite to the outer periphery of the rotor, and coils arranged to excite each of the first and second stators, The rotor has two rotor members arranged to face each other in the axial direction, and each rotor member has two magnetized layers formed in its axial direction, and each magnetized layer has at least two magnetized layers. The magnetic pole portions of adjacent magnetized layers are magnetized in opposite polarities, and the plurality of magnetic pole portions of each of the first and second stators have different magnetic pole portions in the axial direction of the rotor. The first and second stators are arranged so as to face the magnetized portion of the magnetic layer, and the first and second stators are excited by the coils for each stator, and by sequentially switching the energization of the coils of the first and second stators. Driving the rotor It adopts a motor.

In order to achieve the second object, the present invention employs a stepping motor characterized in that a magnetically permeable material is interposed between the two rotor members in addition to the above configuration. Is what you do.

In order to achieve the third object, the present invention further comprises, in addition to the above-mentioned first structure, a yoke made of a magnetically permeable material, and the yoke is juxtaposed to the stator in the axial direction of the rotor. The yoke is arranged on the rotor at a position different from that of the stator such that an end of the yoke faces a magnetized portion of a magnetized layer different in the axial direction of the rotor. It adopts a step motor.

Further, the present invention provides a first and second rotors each having a cylindrical rotor made of a permanent magnet magnetized in a radial direction, and a plurality of magnetic pole portions arranged to face the outer periphery of the rotor. In a stepper motor having a stator and a coil arranged to excite each of the first and second stators, the stepper motor comprises a magnetically permeable material juxtaposed in the axial direction of the rotor with respect to the first and second stators. Comprising two yokes, the rotor being axially opposed to each other.
It has a first and a second rotor member, a magnetic pole portion of the first and second stators is disposed to face a magnetic pole portion of the first rotor member, and the magnetized portion of the second rotor member is 1st and 2nd
The ends of two yokes arranged above the stator are arranged to face each other, and the polarities of the magnetized portions of the first and second rotor members are shifted from each other by a certain shift angle, so that A stepping motor characterized in that the combined force of the cogging torque received by the first rotor member in relation to the first and second stators and the cogging torque received by the second rotor member in relation to the two yokes is reduced, or A first rotor having a cylindrical rotor composed of radially magnetized elephant crushed stone and a plurality of magnetic pole portions disposed opposite to the outer periphery of the rotor.
And a second stator, and a step motor having a coil arranged to excite each of the first and second stators, wherein the rotor has two magnetized layers formed in the axial direction, The magnetized layer has at least two magnetized portions, and the plurality of magnetic pole portions of each of the first and second stators are arranged so as to face magnetized portions of different magnetized layers in the axial direction of the rotor. And two yokes made of a magnetically permeable material are provided adjacent to the first and second stators, and a plurality of magnetic pole portions of each of the two yokes has a magnetized portion of a magnetized layer different in the axial direction of the rotor. Are arranged so as to face the first and second
The stator and the two yokes are shifted by a certain shift angle in plan, so that the first rotor member
And a stepping motor characterized in that the combined force of the cogging torque received in relation to the stator and the cogging torque received by the second rotor member in relation to the two yokes is reduced.

[0015]

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIGS. 1 to 9 show a first embodiment of a stator motor according to the present invention. In FIG. 1, a rotor 7 is rotatably mounted on a lens barrel base plate 1 about a point 7a as a center of rotation, and is magnetized in a radial direction. In this embodiment, a circumferential direction is divided into two parts. It is magnetized. Further, the rotor 7 has a magnetized layer divided into two layers in the axial direction. In each of the magnetized portions, circumferentially adjacent portions, for example, 7a and 7b are magnetized with opposite polarities.
Adjacent portions of the upper and lower layers, for example, 7a and 7c are magnetized with opposite polarities. That is, for example, the portion 7a is magnetized to the S pole, the portion 7b is magnetized to the N pole, the portion 7c is magnetized to the N pole, and the portion 7d is magnetized to the S pole.

The first stator 8 has magnetic pole portions 8a and 8b, and these magnetic pole portions 8a and 8b are fixed to the lens barrel base plate 1 so as to be adjacent to the rotor 7, and the second stator 9 has magnetic pole portions 9a and 8b. , 9b, and these magnetic pole portions 9a, 9b are fixed to the lens barrel base plate 1 at positions opposite to the first stator 8 so as to be adjacent to the rotor 7.

The first stator 8 and the second stator 9
Unlike the conventional example, the magnetic pole portions 8a, 8b and 9a,
9b are configured to overlap each other in the axial direction of the rotor 7. The magnetic pole portion 8a of the first stator and the magnetic pole portion 9a of the second stator are formed by a magnetized portion 7a on the upper side of the rotor 7,
7b, and the magnetic pole portion 8b of the first stator and the magnetic pole portion 9b of the second stator face the cylindrical portion including the lower magnetized portions 7c and 7d of the rotor 7. It has become.

As described above, the magnetic pole portion 8 of the first stator 8
Since a and 8b and the magnetic pole portions 9a and 9b of the second stator 9 are overlapped in the axial direction of the rotor, the dimension of the lens barrel base plate required by the stator motor in the radial direction (the direction of arrow A) is small. In other words, the lens barrel of the camera can be made compact.

Next, the operation of this embodiment will be described. Assuming now that the initial position of the rotor 7 is at the position shown in FIG. 1, the magnetic pole portion 8a of the first stator 8 is first set to the N pole, and the magnetic pole portion 8b
Is supplied to the coils 5 and 6 such that the magnetic pole portion 9a of the second stator 9 becomes the S pole and the magnetic pole portion 9b becomes the N pole. 2 and 3 show the state of the lower rotor and the stator and the state of the upper rotor and the stator at this time, respectively. In this state, the polarities of the rotor, the respective magnetized portions, and the respective magnetic pole portions of the respective stators facing the magnetized portions are opposite to each other, and the rotor is in a stationary and stable state. If the rotor is at another position before energization, the state shown in FIGS. 2 and 3 will be obtained after energization.

From this state, the magnetic pole portion 8 of the first stator 8
When the energization of the coil 5 is switched such that a becomes the S pole and the magnetic pole portion 8b becomes the N pole, the magnetized portion 7a of the rotor repels the magnetic pole portion 8a magnetized to the S pole, and the magnetized portion 7b At the same time, the magnetized portion 7c of the rotor is repelled by the magnetic pole portion 8b magnetized to the N pole, and the magnetized portion 7d is attracted. As a result, the rotor 7 rotates 90 ° counterclockwise, The position is as shown in FIGS.

When the direction of current supply to the coil 6 is switched from the state shown in FIGS. 4 and 5 so that the magnetic pole portion 9a of the second stator 9 becomes the N pole and the magnetic pole portion 9b becomes the S pole, the N pole is magnetized. The magnetized portion 7b of the rotor repels the magnetized pole portion 9a, and 7a is attracted. At the same time, the magnetized portion 7d of the rotor repels the magnetized pole portion 9b magnetized to the S pole, and the magnetized portion 7c is repelled. It is sucked. As a result, the rotor 7 further rotates 90 ° counterclockwise,
It comes to the position shown in FIGS.

When the power supply to the coil 5 is switched from the state shown in FIGS. 6 and 7 such that the magnetic pole portion 8a of the first stator becomes the N pole and the magnetic pole portion 8b becomes the S pole, the first stator is magnetized to the N pole. The magnetized portion 7b of the rotor is repelled by the magnetic pole portion 8a, the magnetized portion 7a is attracted, and at the same time, the magnetized portion 8b magnetized to the S-pole.
The magnetic pole portion 7d is repelled, and the magnetic pole portion 7c is attracted. As a result, the rotor is further rotated counterclockwise by 90 °, and comes to the position shown in FIGS.

When the energization of the coil is switched from the state shown in FIGS. 8 and 9 so that the magnetic pole portion 9a of the second stator 9 becomes the S pole and the magnetic pole portion 9b becomes the N pole, the S pole is magnetized. The magnetized portion 7a of the rotor is repelled by the magnetic pole portion 9a, and the magnetized portion 7b is attracted. At the same time, the magnetic pole portion 7c is repelled by the magnetized portion 9b magnetized to the N pole, and the magnetic pole portion 7d is attracted. Is done. As a result, the rotor rotates further 90 ° in the counterclockwise direction, and FIG.
It will return to the position shown in FIG.

Thus, the rotor 7 has made one revolution in the counterclockwise direction. Further, in order to rotate the rotor 7 clockwise, the energizing direction of the coils 5 and 6 may be sequentially switched in the same manner as described above.

That is, when the energizing direction of the coil 6 is switched from the state shown in FIGS. 2 and 3 so that the magnetic pole portion 9a of the second stator 9 becomes the N pole and the magnetic pole portion 9b becomes the S pole, the rotor 7 becomes 90
Rotate clockwise to reach the position shown in FIGS. Further, when the energizing direction of the coil 5 is switched so that the magnetic pole portion 8a of the first stator 8 is the S pole and the magnetic pole portion 8b is the N pole, the rotor 7 is moved from the position of FIGS. Rotate further 90 ° clockwise to the position shown. Further, from this state, when the energizing direction of the coil 6 is switched to set the magnetic pole portion 9a of the second stator 9 to the S pole and the magnetic pole portion 9b to the N pole, the rotor 7 is moved from the position of FIGS. Rotate further 90 ° clockwise to position 5. Further, from this state, when the energizing direction of the coil 5 is switched to set the magnetic pole portion 8a of the first stator 8 to the N pole and the magnetic pole portion 8b to the S pole, the rotor 7 further rotates clockwise by 90 ° and returns to the original position. 2 and FIG.

In this embodiment, the rotor is divided into two parts in the circumferential direction, that is, the rotor is magnetized with the S pole and the N pole by 180 °. However, the rotor is divided into four parts and eight parts. It is applicable and the number of divisions is not limited in the present invention.

(Second Embodiment) FIGS. 10 to 15 show a second embodiment of the stator motor of the present invention. In FIG. 10, the first and second rotor members 10, 11 are fixed to both ends of a shaft 12 and are configured to rotate integrally.
This rotor opens and closes the shutter and drives the taking lens as in the first embodiment.

The first rotor member 10 is made of a permanent magnet, has two upper and lower magnetized layers, and each magnetized layer has two magnetized portions. Therefore, the first rotor member has four magnetized portions. Of these magnetized portions, the magnetized portion 10a is magnetized to the S pole, the magnetized portion 10b is magnetized to the N pole, the magnetized portion 10c is magnetized to the N pole, and the magnetized portion 10d is magnetized to the S pole. Also the second
The rotor 11 is also made of a permanent magnet, has two upper and lower magnetized layers, and each magnetized layer has two magnetized portions. Therefore, the second rotor member has four magnetized portions similarly to the first rotor member. Of these magnetized portions, the magnetized portion 11a is magnetized to the S pole, the magnetized portion 11b is magnetized to the N pole, the magnetized portion 11c is magnetized to the N pole, and the magnetized portion 11d is magnetized to the S pole.

In this embodiment, the magnetized portions 10a and 10b and 10c and 10d of the first rotor member, and the magnetized portions 11a and 11b and 11c and 11d of the second rotor member are circular as shown in FIG. It is divided by 180 ° in the circumferential direction. Then, the magnetized portions 10a and 10c of the first rotor member
Are in phase with each other in the rotation direction, that is, are aligned in the axial direction, so that the magnetized portion 10 of the first rotor member
b and 10d have the same phase in the rotation direction. Also,
The magnetized portions 11a and 11c of the second rotor member have the same phase in the rotation direction, and the magnetized portions 11b and 11d have the same phase in the rotation direction.

However, the first rotor member 10 and the second rotor member 11 have different phases in the magnetized rotation direction. That is, the boundary line 10e between the magnetized portions of the first rotor member and the boundary line 11e between the magnetized portions of the second rotor member are at an angle,
For example, it is configured to be shifted by α (see FIG. 11).

The two magnetic pole portions of the first stator 8 face the first rotor member 10 and the two magnetic pole portions of the second stator 9
The two magnetic pole portions are arranged on the lens barrel base plate 1 (see FIG. 11) so as to face the second rotor 11. In each stator, the center of the two magnetic pole portions of each stator is located at a position on a radius R (see FIG. 11) which is on a concentric circle of the lens barrel base plate 1 passing through the rotation centers of the first and second rotor members. The angle β (see FIG. 12) formed by the two positions where the two magnetic pole portions of each stator face each rotor member is the center of the rotor is 180 ° / 180 °, where n is the number of divisions magnetized on the rotor member. About n is preferable. In this embodiment, since the rotor is divided into two in the circumferential direction by the magnetization of the S pole and the N pole, β = 90 ° in this embodiment.

The phase difference α between the magnetizations of the first rotor member 10 and the second rotor member 11 is α = 180 ° -1.
Since it is preferably 80 ° / n, in this embodiment,
Since n = 2, the configuration is such that α = 90 °.

Each magnetic pole portion 8a, 8b, 9 in FIG.
12 and 1 so that the arrangement relationship between the first rotor member 11a and the second rotor member 11 can be easily understood.
3, 14 and 15 are shown in plan views. That is, FIG.
Shows the relationship between the second rotor member 11 and the magnetic pole portion 9a of the second stator, FIG. 13 shows the relationship between the second rotor member 11 and the magnetic pole portion 9b of the second stator, and FIG. FIG. 15 shows the relationship between the rotor member 10 and the magnetic pole portion 8a of the first stator, and FIG. 15 shows the relationship between the first rotor member 10 and the magnetic pole portion 8b of the first stator.

The operation for driving the rotor in the second embodiment is the same as the operation in the first embodiment,
6 can be performed by switching the energization. Therefore, detailed description is omitted.

In the second embodiment, the magnetic pole portion of the stator does not need to protrude outside or inside the rotor in the radial direction of the lens barrel base plate 1, so that the above-described dimension A can be further reduced.

(Third Embodiment) The third embodiment has a drawback caused by a change in the configuration of the stepping motor performed in the first embodiment to reduce the radial dimension of the lens barrel base plate. (Reduction in the generation of driving torque) while maintaining the dimensions small.
That is, in the structure of the stepping motor of the first embodiment (see FIG. 1), since the magnetization direction of the rotor of the stepping motor is the radial direction, most of the magnetic flux in the rotor 7 is reduced.
a to the magnetized portion 7b and from the magnetized portion 7d to the magnetized portion 7c. As a result, as the magnetic circuit, the magnetic pole portion 8a of the stator 8 → the magnetized portion 7a of the rotor 7 → the magnetized portion 7b → the magnetic pole portion 9a of the stator 9 → the magnetic pole portion 9b → the magnetized portion 7d of the rotor 7
→ Magnetized part 7 c → Magnetic pole part 8 b of stator 8 → (Magnetic pole part 8
The magnetic circuit is connected through the path a). This magnetic circuit has a drawback that a driving torque equivalent to that of the conventional step motor shown in FIG. 28 is not generated. To eliminate this drawback and provide a magnetic circuit equivalent to the conventional step motor shown in FIG.
a to the magnetized portion 7c and from the magnetized portion 7d to the magnetized portion 7b.

FIGS. 16 and 17 are a perspective view and a sectional view, respectively, of a third embodiment in which the above-mentioned disadvantages have been eliminated. 16 and 17, the rotor member is composed of a first rotor member 21 and a second rotor member 22 fixed to each other by a rotor shaft 24, which will be described in detail later. The first rotor member 21 is made of a permanent magnet, and its surface 21a is magnetized so as to have the S pole and the surface 21b opposite to the surface 21a has the N pole. The second rotor member 22 is made of a permanent magnet, and its surface 22a has an N pole, and a surface 22a opposite to the surface 22a.
b is magnetized so as to be an S pole. The first rotor member 21 and the second rotor member 21 are arranged such that the surface 22a is located below the surface 21a and the surface 22b is located below the surface 21b, that is, the polarity of magnetization is opposite in the vertical direction. 22 is fixed by a rotor shaft 24.

A non-magnetic disk 23 made of a non-magnetic material is disposed between the first rotor member 21 and the second rotor member 22. The rotor shaft 24 includes the main plate 25 and the main plate 2.
6 is rotatably mounted at both ends 24b and 24c, and a first rotor member 21,
The non-magnetic disk 23 and the second rotor member 22 are fixed concentrically. The shaft main body 24a of the rotor shaft 24 is made of a material having a high magnetic permeability such as at least permalloy or soft magnetic iron, so that magnetic flux can easily flow between the first rotor member 21 and the second rotor member 22. The rotor shaft 24 is provided with a gear portion 24d.
Reference numeral 4d is engaged with a lens barrel extending mechanism (not shown), a shutter driving mechanism (not shown), and the like, and drives these. The first rotor member 21, the non-magnetic disk 23, and the second rotor member 22 constitute a rotor.

The magnetic pole portion 108a of the first stator 108 is opposed to the first rotor member 21 with a small gap, and the magnetic pole portion 108b is opposed to the second rotor member 22 with a small gap. Is configured. Similarly, the magnetic pole portion 109a of the second stator 109 faces the first rotor member 21 with a small gap, and the magnetic pole portion 109b faces the second rotor member 22 with a small gap. Is configured.

The first shaft body 24a of the rotor shaft 24
The magnetic flux heading toward the inner diameters of the rotor member 21 and the second rotor member 22 may be changed as necessary,
Depending on the state of the external magnetic circuit formed by the second stator 109 and the second stator 109, it is possible to pass between the inner diameter portions of the first rotor member and the second rotor member.

With such a configuration, the first rotor member 2
Regardless of whether the first and second rotor members 22 are formed of anisotropic magnets or isotropic magnets, a magnetic circuit equivalent to the magnetic circuit of a conventional step motor can be obtained.

(Fourth Embodiment) FIG. 18 is a sectional view of a rotor shaft in a fourth embodiment of the step motor of the present invention.
As is apparent from FIG. 18, a gap is provided between the first rotor member 21 and the second rotor member 22 in the fourth embodiment. Thus, the lower surface of the first rotor member and the second
Magnetic flux is prevented from passing between the upper surface of the rotor member and the rotor member.

(Fifth Embodiment) This fifth embodiment is directed to, for example, a step motor structure which can be used for extending the photographing lens without conducting electricity for extending the photographing lens even during the exposure operation in the camera. It was done. The sixth and seventh embodiments described later are intended similarly to the fifth embodiment.

FIGS. 19 to 23 show a fifth embodiment of the stepping motor according to the present invention. In FIG. 19, the rotor includes a first rotor member 201 and a second rotor member fixed to each other with a rotor shaft.
It comprises a rotor member 202 and is rotatably attached to a main plate (not shown). The first rotor member 201 is divided into four parts in the circumferential direction, and the S pole and the N pole are alternately magnetized, and the magnetization direction is the radial direction. Similarly, the second rotor member 202
Is divided into four parts in the circumferential direction, the S pole and the N pole are alternately magnetized, and the magnetization direction is the radial direction. A first stator 203,
The second stator 204 includes these magnetic pole portions 203a, 20
Reference numerals 3b, 204a, and 204b (see FIG. 20) are arranged to face the magnetized portion on the outer periphery of the first rotor 201. The coils 205 and 206 are arranged to excite the stator. The yokes 207 and 208 are arranged such that their ends 207a, 207b, 208a and 208b (see FIG. 21) face the second rotor member 202. Stators 203 and 204 and yokes 207 and 20
8 is made of a magnetically permeable material, and the end 207a of the yoke 207
Has substantially the same shape as the magnetic pole portion 203a of the stator 203. Similarly, the end portion 207b and the magnetic pole portion 203b, the end portion 208a and the magnetic pole portion 204a, and the end portion 208b and the magnetic pole portion 2
04b has almost the same shape.

FIG. 20 is a plan view showing the relationship between the first rotor member 201 and the stators 203 and 204.
1 is a plan view showing the relationship between the second rotor member 202 and yokes 207 and 208. As can be seen simultaneously from FIGS. 20 and 21, the end portions 207 of the yokes 207, 208 can be seen.
a, 207b, 208a, 208b and the second rotor member 2
The relationship between the polarity of the magnetized portion 02 and the polarity of the stator 203, 20
4 is shifted by 45 ° from the relationship between the magnetic pole portions 203a, 203b, 204a, and 204b and the polarity of the magnetized portion of the first rotor member 201. That is, in this embodiment, the magnetic pole portions 203a, 203 of the stators 203, 204
b, 204a, 204b and the ends 207a, 207b, 208a, 208b of the yokes 207, 208 are at the same position in plan view, so that the magnetized portion of the second rotor member 202 is magnetized of the first rotor member 201. 45 ° to part
It is arranged so that it may shift.

This deviation angle is 22.5 ° when the number of divisions of the magnetized portions of the first rotor member and the second rotor member is eight.
The general formula of the shift angle α is α, where n is the number of divisions.
= 1/2360 ° / n.

FIG. 22 is a characteristic diagram of the cogging torque. In the figure, the vertical axis represents the generated cogging torque, and +
The side is a force acting in the direction to return the rotation, and the-side is a force acting in the direction to advance the rotation. The horizontal axis is the rotation angle of the rotor (first rotor member). At 0 °, the first rotor member is in the state shown in FIG. Also, the first
The cogging torque received by the rotor member 201 from the relationship with the stators 203 and 204 is indicated by a in FIG.

From FIG. 22, the rotor is changed from FIG.
° reduce cogging torque in the vicinity of the rotational position, i.e., 0 ° or readily 0 ° or 90 ° the torque t ₁ is small impact or the like required in order to proceed to the rotational position of 90 °
It turns out that it moves to the position of. The cogging torque received by the second rotor member 202 in relation to the yokes 207 and 208 is indicated by b in FIG. This torque is 45 ° out of phase with respect to a.

First rotor member 201 and second rotor member 2
02 are integrally rotated, so that the cogging torque received by the entire rotor is a combined force of the forces a and b. This combined force is indicated by c in the figure. c is 45 ° rotated torque required to advance to the position of the back or 90 ° to the position of 0 ° in position t ₂ becomes, which is larger than the t ₁ above. Therefore, it can be said that the rotor is stably held at the 45 ° position. In addition, when the first rotor member 201 is at the position of 0 ° or 90 °, that is, when the first rotor member 201 is at the position shown in FIG. 19 or the position rotated 90 ° from FIG. As shown in FIG. 22, the cogging torque to be overcome is t ₃ in the conventional example, but is t ₂ (t ₃ > t ₂ ) in this embodiment. Since the driving force generated by the stator motor of this embodiment is obtained by subtracting the cogging torque from the electromagnetic force generated by energizing the coils 205 and 206, the maximum cogging torque is reduced. That is, there is an advantage that the driving force generated by the stator motor increases from t ₃ to t ₂ .

In this embodiment, there are two rotor members, a first rotor member and a second rotor member.
08 is such that the stators 203 and 204 face the rotor member facing the other rotor member, so that the yoke 20
7, 208 and the stators 203, 204 can be arranged at positions where they do not interfere with each other.

FIG. 23 is a sectional view of this embodiment. As shown in FIG. 23, the yokes 207 and 208
So as not to interfere with the 5,206, because of the central position of the rotor member within a distance of L _1, L _2, yoke 207,2
08 can be placed within the thickness A ₁ of the coil 205 and 206, the step motor total thickness does not become thick as compared with the prior art.

(Sixth Embodiment) FIGS. 24 and 25 are a perspective view and a plan view of a sixth embodiment, respectively. In these figures, the rotor 209 is divided into four parts in the circumferential direction.
The S pole and the N pole are alternately magnetized. The magnetization direction is the radial direction. The stators 203 and 204 face the lower part of the magnetized part of the rotor 209, and the yokes 202 and 208 face the upper part. Yokes 207, 208
As shown in FIG. 25, the stators 203 and 204 are arranged so as to face the position of the magnetized portion of the rotor which is shifted from the position facing the rotor by α, that is, 45 °. With such a configuration, the same effect as in the fifth embodiment can be obtained.

(Seventh Embodiment) The seventh embodiment is directed to a structure of a step motor in which the first embodiment is further improved from the same viewpoint as the fifth embodiment or the sixth embodiment. . In the stepping motor of the first embodiment, the cogging torque is too strong at the rotor positions shown in FIGS. 2, 3, 6, and 8, and a sufficient driving force is obtained even when the coils 5 and 6 are energized. In the positions of the rotors shown in FIGS. 4, 5, 8, and 9, sufficient cogging torque is not generated, and when the coil is not energized, the rotor is not stably held at the positions shown in the drawings. . Even in this case, the same effect as in the fifth and sixth embodiments can be obtained by disposing the yoke at a position shifted by half the magnetized pitch of the rotor with respect to each stator. That is, FIG.
The cogging torque at the rotor position shown in FIGS. 3, 6, and 8 is reduced, and the cogging torque at the rotor position shown in FIGS. 4, 5, 8, and 9 is increased to generate a large driving force. And a step motor in which the rotor is stably held at four positions.

FIG. 26 is a perspective view of the stepping motor according to the seventh embodiment. The first yoke 310 is fixed to the main plate 301. The first yoke 310 has ends 310 a and 310 b at positions shifted by 90 ° about the rotor 307 with respect to the magnetic pole portions 308 a and 308 b of the stator 308. The second yoke 311 is fixed to the main plate 301.
The second yoke 311 moves 90 degrees around the rotor 307 with respect to the magnetic pole portions 309 a and 309 b of the second stator 309.
The ends 311a and 311b are provided at positions shifted by °.
FIG. 27 is a plan view of the seventh embodiment.

With this configuration, for the same reason as in the fifth embodiment, the same amount of cogging torque is generated every 45 ° rotation of the rotor, and the rotor can be stably held every 45 °. Further, since the largest one of the cogging torques becomes small, a large driving force can be obtained by energizing the coil. Further, since the first yoke 310 and the second yoke 311 can be arranged on the plane between the coil 305 and the rotor 307 and between the coil 306 and the rotor 307, the dimension in the A direction (radial direction) as shown in FIG. Does not grow.

[0057]

As described above, according to the present invention,
A plurality of magnetized portions are formed on the rotor in the axial direction, and the magnetic pole portion of the stator is arranged so as to be overlapped in the axial direction of the rotor so as to face the magnetized portion of the rotor. Can be smaller.

According to the present invention, the step motor can be reduced in planar dimension and the driving torque can be reduced by arranging a yoke of a magnetically permeable material, that is, a rotor shaft, in the center between the two rotor members. Can be prevented from lowering.

In addition to the above-described effects, according to the present invention, the rotor is divided into two rotor members, or the rotor is divided into two magnetized portions, and the angle of the magnet with respect to the stator is a half of the magnetized pitch. By arranging the yoke at a position shifted in the circumferential direction so as not to interfere with the stator, the following effects can be achieved without impairing compactness.

An appropriate cogging torque is generated at each stop position of the rotor, so that the rotor can be stably held even when energization of the coil is cut off, and a large driving force can be obtained by energizing the coil.

Further, conventionally, the acceleration pattern starting from the stable position and the acceleration pattern starting from the unstable position are different from each other. However, in the present invention, the driving torque (conduction torque-cogging torque) is constant. Therefore, the same acceleration pattern can be used in any of the aforementioned acceleration starts, and the control method can be simplified.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of a step motor according to the present invention.

FIG. 2 is a plan view showing a rotational position of a rotor corresponding to an excited state of a stator.

FIG. 3 is a plan view showing a rotational position of a rotor corresponding to an excited state of a stator.

FIG. 4 is a plan view showing a rotational position of a rotor corresponding to an excited state of a stator.

FIG. 5 is a plan view showing a rotational position of a rotor corresponding to an excited state of a stator.

FIG. 6 is a plan view showing a rotational position of a rotor corresponding to an excited state of a stator.

FIG. 7 is a plan view showing a rotational position of a rotor corresponding to an excited state of a stator.

FIG. 8 is a plan view showing a rotational position of a rotor corresponding to an excited state of a stator.

FIG. 9 is a plan view showing a rotational position of a rotor corresponding to an excited state of a stator.

FIG. 10 is a perspective view of a step motor according to a second embodiment of the present invention.

FIG. 11 is a plan view of the second embodiment.

FIG. 12 is a plan view showing a relationship between a magnetic pole part of one stator and a magnetized part of one rotor.

FIG. 13 is a plan view showing a relationship between a magnetic pole part of one stator and a magnetized part of one rotor.

FIG. 14 is a plan view showing a relationship between a magnetic pole part of one stator and a magnetized part of one rotor.

FIG. 15 is a plan view showing a relationship between a magnetic pole part of one stator and a magnetized part of one rotor.

FIG. 16 is a perspective view of a step motor according to a third embodiment.

FIG. 17 is a plan view of a stepping motor according to a fourth embodiment.

FIG. 18 is a sectional view of a rotor shaft of the step motor.

FIG. 19 is a perspective view of a stepping motor according to a fifth embodiment.

FIG. 20 is a plan view of a rotor and a stator of the step motor.

FIG. 21 is a plan view of a rotor and a yoke of the step motor.

FIG. 22 is a characteristic diagram relating to cogging torque of a step motor.

FIG. 23 is a sectional view of a step motor.

FIG. 24 is a perspective view of a stepping motor according to a sixth embodiment.

FIG. 25 is a plan view of a step motor.

FIG. 26 is a perspective view of a stepping motor according to a seventh embodiment.

FIG. 27 is a plan view of a step motor.

FIG. 28 is a plan view of a conventional step motor.

FIG. 29 shows FIG. 2 with the rotor in different positions;
FIG. 8 is a plan view similar to FIG.

FIG. 30 shows FIG. 2 with the rotor in different positions;
FIG. 8 is a plan view similar to FIG.

FIG. 31 shows FIG. 2 with the rotor in different positions
FIG. 8 is a plan view similar to FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lens barrel base plate 5, 6 coil 7 rotor 8 first stator 9 first stator 10 first rotor member 11 second rotor member 105, 106 coil 108, 109 stator 201 rotor 203, 204 stator 205, 206 coil 207, 208 yoke

Claims (12)

(57) [Claims] A first rotor having a plurality of magnetic pole portions disposed opposite to an outer periphery of the rotor; a first stator having a plurality of magnetic pole portions disposed opposite to an outer periphery of the rotor;
And a coil arranged to excite each of the second stators, wherein the rotor has two magnetized layers formed in its axial direction, and each magnetized layer has at least two magnetized layers. A magnetic pole portion, and magnetic pole portions of adjacent magnetized layers are magnetized in opposite polarities, and the first and second
The plurality of magnetic pole portions of each of the stators are arranged so as to face magnetized portions of different magnetized layers in the axial direction of the rotor, and the first and second stators are excited for each stator by the coil, and A step motor for driving the rotor by sequentially switching the energization of the coils of the first and second stators. A first rotor having a plurality of magnetic pole portions disposed opposite to an outer periphery of the rotor; a first stator having a plurality of magnetic pole portions disposed opposite to an outer periphery of the rotor;
And a coil arranged to excite each of the second stators, wherein the rotor has two rotor members arranged axially opposed to each other, and each rotor member has its shaft Two magnetized layers are formed in each direction, each magnetized layer has at least two magnetized portions, and the magnetic pole portions of adjacent magnetized layers are magnetized to opposite polarities, and The plurality of magnetic pole portions of each of the first and second stators are arranged so as to face magnetized portions of different magnetized layers in the axial direction of the rotor, and the first and second stators are fixed by the coils to the respective stators. A step motor which is energized to drive the rotor by sequentially switching energization of the coils of the first and second stators. 3. The step motor according to claim 2, wherein the center between the magnetic pole portions of the stator is on the same circumference as the radial position of the lens barrel base plate through which the rotation center of the rotor passes. Characterized step motor. 4. The stepping motor according to claim 2, wherein each of said rotor members has a boundary between its magnetized portions shifted from each other in a rotational direction. 5. The step motor according to claim 2, wherein a magnetically permeable material is interposed between said two rotor members. 6. The step motor according to claim 5, wherein said magnetically permeable material is a rotor shaft for fixing said rotor member at both ends thereof. 7. The step motor according to claim 5, wherein a gap is provided between the two rotor members. 8. The step motor according to claim 1, further comprising a yoke made of a magnetically permeable material, wherein the yoke is juxtaposed to the stator in the axial direction of the rotor, and the end of the yoke is aligned in the axial direction of the rotor. A step motor, wherein a yoke is arranged on a rotor at a position different from that of the stator so as to face magnetized portions of different magnetized layers. 9. A rotor having a cylindrical shape made of a permanent magnet magnetized in a radial direction, a first and a second stator having a plurality of magnetic pole portions disposed to face the outer periphery of the rotor, and
And a coil arranged to excite each of the second stator, wherein two yokes made of a magnetically permeable material juxtaposed in the axial direction of the rotor with respect to the first and second stators are provided. The rotor has first and second rotor members arranged axially opposite to each other, and the magnetic pole portions of the first and second stators face the magnetic pole portions of the first rotor member. The ends of two yokes arranged above the first and second stators are arranged to face the magnetized portion of the second rotor member, and the first and second rotors are arranged. When the polarities of the magnetized portions of the members are shifted from each other by a certain shift angle, the cogging torque received by the first rotor member in relation to the first and second stators and the second rotor member are moved between the two yokes. The combined force with the cogging torque received in the relationship Step motor, wherein the door. 10. A rotor having a cylindrical shape made of radially magnetized elephant crushed stone, a first and a second stator having a plurality of magnetic pole portions disposed opposite to the outer periphery of the rotor. No.
A step motor having coils arranged to excite each of the first and second stators, wherein the rotor has two magnetized layers formed in the axial direction, and each magnetized layer has at least two magnetized layers. A plurality of magnetic pole portions of each of the first and second stators are arranged so as to face magnetized portions of different magnetized layers in the axial direction of the rotor;
And two yokes made of a magnetically permeable material are provided adjacent to the second stator, and a plurality of magnetic pole portions of each of the two yokes face magnetized portions of different magnetized layers in the axial direction of the rotor. The cogging torque that the first rotor member receives in relation to the first and second stators due to the arrangement of the first and second stators and the two yokes being displaced by a certain displacement angle in a plane. A stepping motor for reducing the combined force of the second rotor member and the cogging torque received by the second rotor member in relation to the two yokes. 11. The stepping motor according to claim 9, wherein the angle of deviation is 360 · 360 °, where n is the number of magnetized portions of the magnetized portion facing the stator. /
n is a stepping motor. 12. A camera, wherein the step motor according to claim 1 is arranged in a lens barrel.