JPH07245928A - Step motor - Google Patents

Abstract

PURPOSE:To reduce the overall size of a step motor by shortening the dimensions of stator while increasing the exciting force of the step motor. CONSTITUTION:Coils 1, 2, 3, 4 are disposed for the upper and lower pole parts of stators 8, 9 while directing the axial direction thereof toward the pole parts. The step motor comprises a cylindrical rotor 107 having a plurality of radially magnetized parts arranged at a constant pitch while altering the polarity in the peripheral direction, a plurality of stators 8, 9 each comprising a first pole part disposed oppositely to the outer periphery of the rotor 107 and a second pole part disposed oppositely to the outer periphery of the rotor 107 shifted by one pitch, and coils for exciting the stators 8, 9, wherein the coils are disposed for the first and second pole parts while directing the axial direction substantially toward the pole parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor structure.

[0002]

2. Description of the Related Art It is well known that a stepper motor drives a shutter blade of a camera or a photographing lens. An example of such a step motor is disclosed in Japanese Utility Model Laid-Open No. 63-113127. In this conventional step motor, a rotor magnetized in the radial direction as shown in FIG. 12 and a plurality of magnetic poles facing the outer circumference of the rotor are provided so that the step motor can be easily arranged in the lens barrel of the camera. And a plurality of coils for exciting the stator are arranged in a substantially arc shape.

In FIG. 12, reference numeral 101 denotes a circular lens barrel base plate, and 102 denotes a rotor rotatably attached to the mirror base plate 101 at a portion 102a.
For example, 02 is divided into four in the circumferential direction as shown in FIG. 13, and S poles and N poles are alternately magnetized. Code 10
Reference numerals 3 and 104 denote stators, and these stators are formed with magnetic pole portions 103a and 104b facing the outer circumference of the rotor 102.

Reference numerals 105 and 106 denote stators 103 and 104.
Shows a coil for exciting. Then, the rotor is rotated by switching the energization of the coil, and the rotation of the rotor is used for driving a shutter blade (not shown) or a photographing lens.

However, in the above-mentioned conventional example, each magnetic pole portion 103a, 103b, 104a, 104b is shown in FIG.
As shown in FIG. 2, the diameter D of the lens barrel must be set because of the length H between the outer side of the outer magnetic pole part and the inner side of the inner magnetic pole part, which has a limit to reduce the size. There was a limit to making it smaller.

Therefore, the present applicant has proposed Japanese Patent Laid-Open No. 5-336729 in order to solve the above-mentioned problems. In the invention of this patent application, a step is made up of a cylindrical rotor magnetized in the radial direction, a plurality of stators having a plurality of magnetic pole portions facing the outer circumference of the rotor, and a coil for exciting the stator. In the motor, the rotor is formed with a plurality of magnetizing layers having different polarities with respect to those adjacent to each other also in the thickness direction (axial direction) of the cylindrical shape, and the plurality of magnetic pole portions of the stator are provided with the magnetizing layers. The magnetic layers are arranged so as to face different layers in the axial direction. Embodiments of the invention will be described below with reference to FIGS.
Will be explained.

Reference numeral 107 denotes a rotor rotatably mounted on the lens barrel base plate 101 with the shaft 107e as the center of rotation. The rotor 107 is magnetized in the radial direction (in this embodiment, the circumference is divided into two parts). It is magnetized so that), and there is a magnetized layer divided into two layers in the axial direction. And, each magnetized portion is, for example, 107a at a portion adjacent in the circumferential direction.
The portions 107b have opposite polarities with respect to the portions, and the portions adjacent to the upper and lower layers, for example, 107b.
The 107c part has opposite polarities to the a part. That is, the 107a portion is the S pole, the 107b portion is the N pole, and the 10
The 7c portion is magnetized to the N pole and the 107d portion is magnetized to the S pole.

Reference numeral 108 denotes a first stator which has magnetic pole portions 108a and 108b and is fixed to the lens barrel base plate 101.
Reference numeral 9 denotes a second stator having magnetic pole portions 109a and 109b to which the lens barrel base plate 1 is fixed, and reference numerals 105 and 106 denote coils for exciting the first stator 108 and the second stator 109.

First stator 108 and second stator 10
Reference numeral 9 denotes magnetic pole portions 108a and 108b and 109a and 109b.
Are arranged so as to overlap in the axial direction of the rotor, and 108a and 109a denote rotors 107a and 107a.
The magnetic pole parts 108b and 109b are arranged so as to face the cylindrical part (upper magnetized layer) formed by the part b.
Cylindrical part consisting of 107c and 107d parts (lower magnetized layer)
To face.

The magnetic pole portions 108a, 108b and 109
Since they are superposed like a and 109b, the dimension of the step motor in the direction of arrow A, that is, the radial direction of the lens barrel base plate is small, and the lens barrel portion of the camera can be made compact.

Next, the operation of this embodiment will be described. Assuming that the initial position of the rotor 7 is the position shown in FIG. 3, first, the magnetic pole portion 108a of the first stator 108 is the N pole, 108b is the S pole, and the second pole is the second pole.
The magnetic pole portion 109a of the stator 109 is an S pole and 109b is an N pole.
The coils 105 and 106 are energized so as to form the poles. The states of the rotor and the stator for the lower layer portion of the rotor at this time are shown in FIG. 4, and the states of the rotor and the stator for the upper layer portion of the rotor are shown in FIG.

From this state, the coil 1 is arranged so that the magnetic pole portion 108a of the first stator 108 becomes the S pole and 108b becomes the N pole.
When the energization direction to 05 is switched, 107a is repelled by the magnetic pole portion 108a and 107b is attracted, 107c is repelled by the magnetic pole portion 108b and 107d is attracted, and the rotor 10
7 rotates to the left and comes to a position rotated by 90 ° as shown in FIGS.

From this state, the coil 10 is arranged so that the magnetic pole portion 109a of the second stator 109 becomes the N pole and 109b becomes the S pole.
6 is switched, the 107b portion is repelled by the magnetic pole portion 109a, and 107a is attracted to the magnetic pole portion 109b.
As a result, 107d repels and 107e is sucked, and the rotor 10
7 rotates to the left and further 9 as shown in FIGS. 8 and 9.
The position is rotated by 0 °.

From this state, when the direction of energizing the coil is switched so that the magnetic pole portion 108a of the first stator 108 becomes the N pole and 108b becomes the S pole, the magnetic pole portion 108a causes 107
b is repelled, 107a is attracted, and the magnetic pole portion 108b causes 1
07d repels and 107c is attracted, and the rotor 107 rotates to the left and reaches a position further rotated by 90 ° as shown in FIGS.

From this state, the coil 10 is arranged so that the magnetic pole portion 109a of the second stator 109 becomes the S pole and 109b becomes the N pole.
6 is switched, the 107a portion is repulsed by the magnetic pole portion 109a and 107b is attracted to the magnetic pole portion 109b.
As a result, 107c repels and 107d is sucked, and the rotor 10
7 rotates to the left, and is again in a position where it is further rotated by 90 ° as shown in FIGS.

This means that the rotor 107 has made one full rotation in the counterclockwise direction. Next, in order to rotate the rotor 107 in the clockwise direction, the energization directions of the coils 105 and 106 may be sequentially switched in the same manner. Switching the energization direction of the coil 106 from the state of FIGS.
When the magnetic pole portion 109a of No. 9 is switched to the N pole and the magnetic pole portion 109b is switched to the S pole, the rotor 107 rotates 90 ° rightward as shown in FIGS.

The energization direction of the coil 105 is switched from the state shown in FIGS. 10 and 11 to the magnetic pole portion 108 of the first stator 108.
When a is switched to the S pole and the magnetic pole portion 108b is switched to the N pole, the rotor 107 further rotates 90 ° to the right as shown in FIGS.

When the energizing direction of the coil 106 is switched from the state shown in FIGS. 8 and 9 to switch the magnetic pole portion 109a of the second stator 109 to the S pole and the magnetic pole portion 109b to the N pole, the rotor 10 is rotated.
7 further rotates 90 ° to the right as shown in FIGS.

When the energizing direction of the coil 105 is switched from the state shown in FIGS. 6 and 7 to switch the magnetic pole portion 108a of the first stator 108 to the N pole and the magnetic pole portion 108b to the S pole, the rotor 10 is rotated.
7 further rotates 90 ° to the right as shown in FIGS.

In the above embodiment, the rotor is divided into two in the circumferential direction, that is, the S pole and the N pole are magnetized by 180 °, but the rotor is divided into four and eight. .

[0021]

However, in the step motor proposed in the invention of the above-mentioned patent application, since the coils 105 and 106 are near the magnetic pole portions 108b and 109b of one of the yokes 108 and 109, the arrows in FIG. As shown in A and B, the magnetic flux leaks in the middle, the magnetic flux is not sufficiently generated from the other magnetic pole portions 108a and 109a, the magnetic layer of the rotor 107 does not sufficiently act, and the driving force does not increase. When the number of turns of the coil is increased, the length of the coil in the axial direction also becomes longer, so that the dimension indicated by L in the figure becomes larger, and when the coil is arranged in the lens barrel of the camera, the step motor occupies most of the circumferential portion. The other mechanical parts will not fit in. As a result, there is a drawback that the lens barrel diameter must be increased. In particular, as shown in FIG. 14, the portions 10 apart from the magnetic poles of the coils 105 and 106
Most of the magnetic flux generated by 5a and 106a are magnetic pole portions 108a, 108b, 109a and 109b as shown by arrows.
However, the magnet 107 does not act on the magnet 107 and does not act on the magnet 107.

[0022]

According to the present invention, there is provided a magnetizing layer having a plurality of magnetizing portions which are cylindrical and have different polarities with respect to those adjacent to each other in the circumferential direction and which are radially magnetized. And a rotor provided with a plurality of the magnetized layers having different polarities with respect to those adjacent to each other in the cylindrical thickness direction (axial direction), and a layer facing the outer circumference of the rotor and different in the axial direction of the rotor. In a step motor comprising a plurality of stators having at least two magnetic pole portions, a first magnetic pole portion and a second magnetic pole portion arranged opposite to each other, and an exciting coil that excites the stator, the exciting coil has an axial direction thereof. Are arranged substantially in the direction of the magnetic poles and arranged at the upper and lower magnetic poles of the stator.

Further, according to the present invention, a rotor having a plurality of magnetized portions which are cylindrical and are magnetized in the radial direction having different polarities with respect to those adjacent to each other in the circumferential direction and arranged at a constant pitch. And a plurality of stators having a first magnetic pole portion located at a position facing the outer circumference of the rotor and a second magnetic pole portion located at a position facing the outer circumference portion of the rotor which is different by one pitch, and a coil for exciting the stator. In the step motor consisting of, the coil is arranged such that the axial direction of the coil is substantially oriented to the magnetic pole portion and is arranged for each of the first magnetic pole portion and the second magnetic pole portion.

[0024]

EXAMPLES Next, examples of the present invention will be described.

(Embodiment 1) FIG. 1 is a perspective view showing a first embodiment of the present invention. Reference numerals 8 and 9 denote stators, and these stators 8 and 9 have magnetic pole portions 8a, 8b, 9a and 9b formed so as to face the outer peripheral magnetized portion of the rotor 107. Reference numerals 1 and 2 denote coils for exciting the stator 8,
These coils have a magnetic pole portion 8 which is excited by the coil 1 when a current is simultaneously applied by an energizing circuit (not shown).
The polarities a and 8b and the polarities of the magnetic pole portions 8a and 8b excited by the coil 2 are the same. Reference numerals 3 and 4 denote coils that excite the stator 9. These coils are magnetic pole portions 9a that are excited by the coil 3 when currents are simultaneously applied by an energizing circuit (not shown).
9b and the magnetic pole portion 9 excited by the coil 4
The polarities of a and 9b are the same.

That is, the coils 1 and 2 function as the coil 105 in the conventional example shown in FIGS. 13 and 14, and the coils 3 and 4 function as the coil 106. The coil 1 is the coil 105 in the conventional example.
The coil having the same number of turns as the 105b part of
Is a coil with the same number of turns as the 105a part of the coil 105, coil 3 is a coil with the same number of turns as the 106b part of the coil 106, and coil 4 is a coil with the same number of turns as the 106a part of the coil 106. And the coils 1, 2,
The axial directions of 3 and 4 are arranged so as to face the approximate center of the rotor 107.

Reference numeral 5 indicates a rotor shaft rotatably attached to a main plate (not shown) by portions 5a and 5b, and the rotor shaft 5 is a rotor 1 made of a permanent magnet.
It is fixed so that 07 is concentric. Also, the rotor shaft 5
Has a gear portion 5c, which is connected to a lens barrel feeding mechanism (not shown), a shutter drive mechanism (not shown), and the like so that these mechanisms can be driven. .

The energization of the coils 1, 2, 3, 4 is switched to rotate the rotor 107. The energization of the coils 1 and 2 is switched simultaneously, and the energization of the coils 3 and 4 is switched simultaneously. Then, driving is performed in the same manner as in the conventional example described with reference to FIGS.

According to the above construction, the coils 1, 2,
The coils 3, 2 and 3 are located near the magnetic poles 8b, 8a, 9b and 9a, respectively, and the axial direction of the coil is arranged toward the magnetic poles or the magnetized layer of the rotor.
As shown in FIG. 2, the magnetic flux generated by energizing the magnetic pole 4 does not leak on the way, and the magnetic pole portions 8b, 8a, 9b,
9a and magnetized portions 107a, 107b, 10 of the rotor
A sufficient driving force is generated by interacting with 7c and 107d.

The number of turns of the coil 1 and the number of turns of the coil 2 are adjusted to be the same as that of the coil 105 of the conventional example.
Since the number of turns of the coil 3 and the number of turns of the coil 4 are the same as that of the coil 105 of the conventional example, the axial lengths of the coils 1, 2, 3, 4 are the same as those of the coils 105, 106.
The length of L _{1 in} FIG. 1 can be made shorter than that of the conventional L (FIG. 13). For this reason, even if the step motor of the present invention is arranged in the lens barrel of the camera, it occupies only a part of the circumferential portion, so that other mechanical parts can be arranged in the remaining circumferential portion.

(Second Embodiment) FIG. 15 is an exploded perspective view showing another conventional motor. This is the actual Kaisho 63-8412
6, the motor disclosed in Japanese Utility Model Laid-Open No. 63-84128 and the like. Reference numeral 201 denotes a rotor formed of a permanent magnet having a plurality of poles magnetized on the outer peripheral portion. Reference numeral 203 denotes a base plate, 202 denotes an upper base plate, and the rotor 201 has a hole 203a in the base plate 203.
Also, it is rotatably attached to the hole 202a of the upper base plate 202. Reference numerals 204, 205, 208, and 209 denote yokes made of a soft magnetic material, and magnetic pole portions 204a, 205a, 208a, 2 located at positions facing the permanent magnet portion of the rotor.
09a, respectively. Reference numerals 206 and 210 denote coil yokes made of a soft magnetic material, and coils 207 and 211 are wound around these coil yokes, respectively. The yokes 204 and 205, the coil yoke 206,
The coil 207 includes holes 203b in the base plate 203 and the upper base plate 2.
Fixed to the hole 202b of No. 02, the yokes 208, 209,
The coil yoke 210 and the coil 211 are fixed to the hole 203c of the base plate 203 and the hole 202c of the upper base plate 202.

In the case of this motor, the coils 207, 211
Is a permanent magnet portion or magnetic pole portion 204a of the rotor 201,
It does not face the direction of 205a, 208a, 208b.
Therefore, even if the coil is energized, a large amount of magnetic flux does not go toward the magnetic pole portion and leaks in various places. Therefore, the driving force was not sufficiently increased.

16 and 17 are views showing a second embodiment of the present invention, FIG. 16 is an exploded perspective view thereof, and FIG. 17 is a sectional view thereof. Reference numerals 301, 302, 303 and 304 denote coils, the total number of turns of the coil 301 and the coil 302 is the same as that of the coil 207 of the above-mentioned conventional example, and the total number of turns of the coil 303 and the coil 304 is the above-mentioned conventional example. Of the coil 211.

Reference numerals 307 and 310 denote connecting yokes made of a soft magnetic material, and the connecting yoke 307 is a yoke 305, 306.
And the holes 312b of the base plate 312 and the upper base plate 311 are connected to each other.
Is fixed together with the yokes 305 and 306 in the hole 311b, the connecting yoke 310 connects the yokes 308 and 309, and is fixed together with the yokes 308 and 309 in the hole 312c of the base plate 312 and the hole 311c of the upper base plate 311.

Similar to the first embodiment described above, the coil is used as a permanent magnet portion or magnetic pole portions 205a and 206 of the rotor 201.
Since the coils are arranged toward the a, 208a, and 309a and for each magnetic pole portion, the magnetic flux due to the energization of the coils does not leak so much in the middle and the rotor 201 is efficiently
The driving force of the motor is increased by acting with the permanent magnet of. Further, according to this, the size of L _{3 in} FIG. 16 is hardly larger than the size of L _{2 in} FIG. 15 and the driving force can be increased.

[0036]

As described above, the coils are arranged toward the magnetic poles and arranged for each magnetic pole, so that the driving force of the motor is increased and the L ₁ dimension in FIG. This has the effect of making the part compact.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of a step motor according to the first embodiment.

FIG. 3 is a perspective view of a conventional step motor.

FIG. 4 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a conventional step motor.

FIG. 5 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a conventional step motor.

FIG. 6 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a conventional step motor.

FIG. 7 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a conventional step motor.

FIG. 8 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a conventional step motor.

FIG. 9 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a conventional step motor.

FIG. 10 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a conventional step motor.

FIG. 11 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a conventional step motor.

FIG. 12 is a plan view of a conventional step motor.

FIG. 13 is a cross-sectional view of a conventional step motor.

FIG. 14 is a cross-sectional view of a conventional step motor.

FIG. 15 is an exploded perspective view of another conventional step motor.

FIG. 16 is an exploded perspective view of a step motor according to a second embodiment of the present invention.

FIG. 17 is a sectional view of a step motor according to a second embodiment.

[Explanation of symbols]

 1 Coil 2 Coil 3 Coil 4 Coil 8 Stator 9 Stator 8a, 8b, 9a, 9b Magnetic pole part 107 Rotor

Claims (2)

[Claims] 1. A cylindrical shape having a magnetizing layer composed of a plurality of magnetized portions which are magnetized in a radial direction and have different polarities with respect to those adjacent to each other in the circumferential direction, and having a thickness direction (axis). Direction), a rotor provided with a plurality of the magnetized layers having different polarities with respect to those adjacent to each other, and a first rotor arranged facing the outer circumference of the rotor and different in the axial direction of the rotor. In a step motor comprising a plurality of stators having at least two magnetic pole portions, a magnetic pole portion and a second magnetic pole portion, and a coil for exciting the stator, the coil has an axial direction substantially oriented to the magnetic pole portion and A step motor, wherein the step motor is arranged for each of the upper and lower magnetic pole portions of the stator. 2. A rotor having a plurality of magnetized portions which are cylindrical and are magnetized in radial directions having different polarities with respect to those adjacent to each other in the circumferential direction, and which are arranged at a constant pitch, Step comprising a plurality of stators having a first magnetic pole portion located at a position facing the outer circumference of the rotor and a second magnetic pole portion located at a position facing the outer circumference portion of the rotor which is different in pitch by one pitch, and a coil for exciting the stator In the motor,
A step motor, wherein the coil has an axial direction substantially facing the magnetic pole portion and is arranged for each of the first magnetic pole portion and the second magnetic pole portion.