JPH06250070A - Lens driving device and stepping motor - Google Patents

Abstract

PURPOSE:To eliminate the inclination or the flexure of a lens or a lens frame and the increase of driving load by concentrically forming a guide part and a male screw part on a guide shaft fixed to the lens frame. CONSTITUTION:The male screw part 3b integrally formed or fixed to the lens or the lens frame, the guide shaft 3 obtained by coaxially forming the guide part, a rotation driving body on which the male screw part 3b of the guide shaft 3 and an engagement female screw part 7f are formed and a bottom board on which a guide hole or a guide tube 2 engaged with the guide part of the shaft 3 is formed are provided. Then, when the rotor 7 of a stepping motor is rotated, the shaft 3, a front-group lens barrel 10 and a back-group lens barrel 4 are moved upward or a downward in an optical axis direction resisting to the actuating force of a spring 11 because of engagement relation between the female screw part 7f of the rotor 7 and the male screw part 3b of the shaft 3. The lens barrels 10 and 4 are guided in the optical axis direction and driven in the optical axis direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device and a step motor, and more particularly to a lens driving device for a camera and a step motor applicable to such a lens driving device. It is not limited.

[0002]

2. Description of the Related Art For example, in a lens driving device for a camera, a guide for holding a lens frame along a guide hole arranged in the optical axis direction in order to accurately move the lens in the optical axis direction. It is desirable to do this by sliding the shaft, but conventionally, in the past, in general, Japanese Patent Laid-Open No. 3-1
As described in Japanese Patent No. 80822 or Japanese Utility Model Laid-Open No. 4-50810, the guide portion for positioning the lens and the screw portion for driving the lens are arranged at different positions.

[0003]

However, in the above-mentioned conventional example, since the force for driving the lens or the lens frame in the optical axis direction acts on the position different from the guide portion due to the structure, the lens or the lens frame is tilted. There is a drawback that the driving load is increased due to increased friction of the guide portion due to misalignment or bending of the lens frame.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a male screw portion integrally formed with or fixed to a lens or a lens frame and a guide shaft having a guide portion coaxially formed, and a male screw portion of the guide shaft are provided. It is characterized in that it is provided with a rotary drive body in which an engaging female screw portion is formed, and a base plate in which a guide hole or a guide tube that fits with the guide portion of the guide shaft is formed.

[0005]

Embodiments of the present invention will now be described with reference to the drawings.

(Embodiment 1) FIGS. 1 to 12 are views showing Embodiment 1 of the lens driving device of the present invention. Of these drawings, FIG. 1 is an exploded perspective view showing main components of the entire lens driving device, FIG. 2 is a sectional view of the lens driving device, FIG. 3 is a plan view thereof, and FIG. FIG. 3 is a perspective view of a step motor unit of the lens driving device.

First, referring to FIGS. 1 to 3, in these drawings, reference numeral 1 denotes a main plate, 2 denotes a guide tube integrally formed with the main plate 1 or fixed to the main plate 1,
Reference numeral 3 denotes a guide shaft. The guide shaft 3 is provided with a fitting 3a slidably fitted in the through hole 2a of the guide tube 2 and a male screw portion 3b engaging with a female screw portion of a rotor 7 described later. There is.

Reference numeral 4 indicates a second lens frame, and the second lens frame 4 has an inner diameter portion 4b for holding a lens (not shown).
have. The second lens frame 4 is fixed to the lower end portion 3d of the guide shaft 3 by the hole 4a.

Reference numeral 7 indicates a rotor, and this rotor 7 is
The outer peripheral portion has a permanent magnet portion magnetized in the radial direction, and the inner diameter portion is formed with a female screw portion 7f that engages with the male screw portion 3b of the guide shaft 3 described above.

As shown in FIG. 4, the permanent magnet portion is magnetized so as to divide the circumference into two, and the permanent magnet portion is axially divided into two parts.
A magnetized layer is provided which is divided into layers. Further, in each magnetized portion, adjacent portions in the circumferential direction, for example, 7a and 7b have opposite polarities, and adjacent portions in upper and lower layers, for example, 7a and 7c have opposite polarities. Has become. That is, the portion 7a is magnetized to the N pole, the portion 7b is magnetized to the S pole, the portion 7c is magnetized to the S pole, and the portion 7d is magnetized to the N pole.

Reference numeral 8 denotes a first stator having magnetic pole portions 8a and 8b and fixed to the lens barrel base plate 1, and 9 denotes a second stator having magnetic pole portions 9a and 9b and fixed to the lens barrel base plate 1. 5 and 6 indicate the first stator 8 and the second stator
The coils for exciting the respective stators 9 are shown. As shown in FIG. 3, these coils 5 and 6 are formed and arranged in an arc shape on the outside of a front lens barrel which will be described later.

The first stator 8 and the second stator 9 are constructed such that their magnetic pole portions 8a and 8b and 9a and 9b overlap in the axial direction of the rotor, respectively.
a and 9a are arranged to face the cylindrical portion (upper magnetized layer) formed of the rotor portions 7a and 7b, and the magnetic pole portion 8
b and 9b are arranged to face the cylindrical portion (lower magnetized layer) formed of the portions 7c and 7d of the rotor 7.

Since the magnetic pole portions 8a and 8b and 9a and 9b are configured to overlap with each other, the direction of the arrow A required by the step motor constituted by the rotor 7, the first stator 8 and the second stator 9 (see FIG. 5). 2), that is, the dimension of the lens barrel base plate 1 in the radial direction is small, and the lens barrel portion of the camera can be made compact.

Referring again to FIGS. 1 to 3, reference numeral 10 indicates a front lens barrel, and a lens (not shown) is held in the inner diameter portion 10c of the front lens barrel 10. Further, the small-diameter upper end portion 3c of the guide shaft 3 is fitted and fixed in a hole 10a (FIG. 1) formed in the front lens barrel, and the front lens barrel 10 is held by the guide shaft 3. The long groove 10b formed on the outer circumference of the front lens barrel 10 engages with the dowel 1a of the base plate 1, and the front lens barrel 10 is guided slidably in the optical axis direction. Therefore, the guide shaft 3 is movable only in the optical axis direction and is in a state in which rotation is prohibited.

Reference numeral 4 indicates a rear group lens barrel, and this rear group lens barrel 4
A lens (not shown) is held in an inner diameter portion 4b of the rear lens barrel, and a small-diameter lower end portion 3d of the guide shaft 3 is fitted and fixed in a hole 4a formed in the rear lens barrel 4. 4 is held by the guide shaft 3. The optical axes of the lens (not shown) held by the rear group lens barrel 4 and the lens (not shown) held by the front group lens barrel 10 described above are made to coincide with each other. By moving the rear lens barrel 4 together in the optical axis direction, the focusing operation is performed.

Reference numeral 11 indicates a compression spring arranged between the rear lens barrel 4 and the base plate 1. The compression spring 1
1 biases the rear lens barrel 4 downward. The rear group lens barrel 4 is fixed to the guide shaft 3, and the front group lens barrel 10 and the rotor 7 are fixed to the guide shaft 3. 3, the front lens barrel 10 and the rotor 7 are integrally biased downward. Further, 12 indicates a steel ball (FIGS. 1 and 2), and the steel ball 12
Is a spot facing portion 2b of the guide tube 2 and a taper portion 7e of the rotor 7.
It is arranged so as to be sandwiched between the two and to reduce the load when the rotor 7 rotates.

When the rotor 7 rotates, the guide shaft 3 whose rotation is prohibited as described above is moved up or down depending on the direction of rotation by the engagement of the male screw portion 3b and the female screw portion 7f.

Next, the operation of the lens driving device according to this embodiment with the rotation of the rotor will be described. First, FIGS.
The operation of the step motor for rotating the rotor will be described in advance with reference to FIG. 2 (see also FIGS. 1 and 4).

Now, assume that the rotor 7 is in the initial position (FIGS. 1 and 4). In this state, the magnetic pole portion 8a of the first stator 8 becomes the S pole, the magnetic pole portion 8b becomes the N pole, the magnetic pole portion 9a of the second stator 9 becomes the N pole, and the magnetic pole portion 9b becomes the S pole. Then, the coils 5 and 6 are energized.

As a result, the rotor and the stator relating to the upper layer portion of the rotor are in the state shown in FIG. 5, and the rotor and the stator relating to the lower layer portion of the rotor are in the state shown in FIG. From this state, when the energizing direction of the coil 5 is switched so that the magnetic pole portion 8a of the first stator 8 becomes the N pole and the magnetic pole portion 8b becomes the S pole, the portion 7 of the rotor 7 with respect to the magnetic pole portion 8a is changed.
a is repulsed and the portion 7b is attracted, and the magnetic pole portion 8
The portion 7c of the rotor 7 repels the portion b and the portion 7c
d is aspirated. As a result, the rotor 7 rotates counterclockwise and comes to a position rotated by 90 ° as shown in FIGS. 7 and 8.

From this state, the magnetic pole portion 9a of the second stator 9 is
Becomes the S pole, and the magnetic pole portion 9b becomes the N pole.
When the energization direction is switched to, the portion 7b repels the magnetic pole portion 9a, the portion 7a is attracted, the portion 7d repels the magnetic pole portion 9b, and the portion 7c is attracted. As a result, the rotor 7 further rotates counterclockwise, and
As shown in 0, it comes to a position rotated by 90 °.

From this state, the magnetic pole portion 8a of the first stator 8 is
Becomes the S pole and the magnetic pole part 8b becomes the N pole.
When the energization direction is switched to, the portion 7b repels the magnetic pole portion 8a, the portion 7a is attracted, and the portion 7d repels the magnetic pole portion 8b and the portion 7c is attracted. As a result,
The rotor 7 further rotates counterclockwise, and
As shown in, come to a position rotated by 90 °.

From this state, the magnetic pole portion 9a of the second stator 9 is
Becomes the N pole, and the magnetic pole part 9b becomes the S pole.
When the energizing direction is switched to, the portion 7a repels the magnetic pole portion 9a, the portion 7b is attracted, the portion 7c repels the magnetic pole portion 9b, and the portion 7d is attracted. As a result, the rotor 7 rotates counterclockwise and comes to a position further rotated by 90 ° as shown in FIGS.

As a result, the rotor 7 has rotated once in the counterclockwise direction. In order to rotate the rotor 7 in the clockwise direction, the energizing directions of the coils 5 and 6 may be sequentially switched in the same manner as described below.

When the energizing direction of the coil 6 is switched from the state shown in FIGS. 5 and 6 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 rotor 7 becomes 11. Rotate 90 ° clockwise as shown in FIG. When switching the energization direction of the coil 5 from the state of FIG. 11 and FIG. 12 so that the magnetic pole portion 8a of the first stator 8 becomes the N pole and the magnetic pole portion 8b becomes the S pole, the rotor 7 of FIG. As shown in FIG. 10, further rotate 90 ° clockwise. Switching the energization direction of the coil 6 from the state of FIGS. 9 and 10, the magnetic pole portion 9a of the second stator 9 becomes the N pole,
When the magnetic pole portion 9b is set to the S pole, the rotor 7 rotates 90 ° clockwise as shown in FIGS. When the energizing direction of the coil 5 is switched from the state shown in FIGS. 7 and 8 so that the magnetic pole portion 8a of the first stator 8 becomes the S pole and the magnetic pole portion 8b becomes the N pole, the rotor 7 becomes the rotor of FIGS. Further rotate 90 ° clockwise as shown in.

In this embodiment, the rotor is divided into two in the circumferential direction, that is, the S pole and the N pole are magnetized by 180 °, respectively. However, the number of divisions does not limit the present invention.

Next, the operation of the lens driving device will be described with reference to FIGS. 1 to 3 again. When the rotor 7 of the step motor rotates as described above, the female screw portion 7f of the rotor 7 and the guide shaft 3 are rotated. Due to the engagement relationship of the male screw 3b,
The guide shaft 3, the front lens barrel 10, and the rear lens barrel 4 move in the optical axis direction, that is, in the upward or downward direction in FIG. 1, against the acting force of the spring 11. The front lens barrel 10 and the rear lens barrel 4 are guided in the optical axis direction because the guide shaft 3 is fitted in the guide tube 2, and the front lens barrel 1 is also used.
0, since a force for driving the rear lens barrel 4 in the optical axis direction is applied to the guide shaft 3, an unreasonable force is not applied to the front lens barrel 10 and the rear lens barrel 4. These lens barrels do not tilt or bend, and the driving load is small.

Further, since the guide shaft 3 has a guide portion and a male screw portion formed in the optical axis direction, the dimension in the width direction of the guide shaft 3 seen in the plan view of FIG. 3 may be small. Therefore, the camera can be made compact. Further, by using the rotor (rotor) of the motor as the rotary driving body having the female screw portion 7f that engages with the male screw portion 3b of the guide shaft 3, it is possible to make it compact and to use it from an actuator such as another motor. Since there is no transmission loss as compared with the case where a driving force is transmitted to the rotary drive body using a gear or the like, it is possible to drive with a small driving force.

(Embodiment 2) FIG. 13 is a sectional view showing Embodiment 2 of the lens driving device of the present invention. In FIG. 13, reference numeral 107 indicates a drive gear as a rotary driving body that performs a rotational motion to move the guide shaft 3 in the vertical direction. Inside the drive gear 107, the male screw portion 3b of the guide shaft 3 is engaged. Is formed, and a gear portion 107a is formed on the outer peripheral portion thereof. 1
Reference numeral 08 denotes a pinion gear, and this pinion gear 108 is engaged with the gear portion 107a of the drive gear 107. 10
Reference numeral 9 denotes a motor, and this motor 109 is fixed to the main plate 1, and a pinion gear 108 is fixed to its output shaft. When the motor 109 is driven to rotate the output shaft, the pinion gear 108 rotates, the rotational force, that is, the driving force is transmitted to the drive gear 107, and the drive gear 107 rotates. The rotation direction of the drive gear 107 drives the front lens barrel 10 and the rear lens barrel 4 upward or downward in the optical axis direction as in the first embodiment.

In this embodiment, the same effect as that of the first embodiment is achieved, except that the driving force transmitted by the engagement between the pinion gear 108 and the gear portion 107a of the drive gear 107 is lost according to the transmission efficiency, that is, the compact structure. It is possible to obtain the effects such as an increase in the number and prevention of tilting and bending of the lens barrel.

(Embodiment 3) FIG. 14 is a plan view showing Embodiment 3 of the lens driving device of the present invention. The third embodiment is directed to a step motor having another structure which can be used in place of the structure of the step motor in the lens driving device of the first embodiment.

In FIG. 14, reference numeral 207 is engaged with a permanent magnet portion which is divided into four in the circumferential direction and is magnetized with S poles and N poles alternately and a male screw portion of a guide shaft (not shown). The rotor in which the female screw part 207f was formed is shown. 208, 2
Reference numeral 09 designates stators, and these stators have rotor 2
Magnetic poles 208a, 208b, so as to face the outer periphery of 07.
209a and 209b are formed. 205, 206
Indicates a coil for exciting the stators 208 and 209.

Also in this step motor, the first embodiment
The rotor 207 can be rotated by switching the energization of the coils 205 and 206 as described above. The front lens barrel and the rear lens barrel are attached to the guide shaft (not shown) in the same manner as in the first embodiment. Therefore, the rotation of the rotor causes the lens barrel to move to the optical axis as in the first embodiment. Can be moved in the direction. Compared to the first embodiment, the third embodiment has a large radial dimension L of the stator. For this reason, the compactness is somewhat lost, but it is sufficiently compact as compared with the conventional one. Regarding other effects, the same effects as those of the first embodiment can be obtained.

Fourth Embodiment The fourth embodiment (and other embodiments described later) is intended to improve the structure of the step motor itself as used in the lens driving device of the first embodiment. However, its application is Example 1
It is not limited to the lens driving device as described above.

15 and 16 are a perspective view and a sectional view of a step motor according to the fourth embodiment. In FIGS. 15 and 16, reference numeral 307 denotes a rotor, and this rotor 307
Has a permanent magnet portion radially magnetized in the outer peripheral portion. As shown in FIGS. 15 and 16, the permanent magnet portion is magnetized so as to divide the circumference into two parts, and is provided with a magnetized layer divided into two layers in the axial direction. The magnetized portions are adjacent to each other in the circumferential direction, for example, 307a and 307b.
Have opposite polarities to each other, and the adjacent portions of the upper and lower layers, for example, 307a and 307c have opposite polarities. That is, the portion 307a is magnetized to the S pole, the portion 307b is magnetized to the N pole, the portion 307c is magnetized to the N pole, and the portion 307d is magnetized to the S pole.

Reference numerals 308 and 309 denote stators. These stators 308 and 309 are magnetic pole portions 308a, 308b, and 3 so as to face the magnetized portions on the outer circumference of the rotor 307.
09a and 309b are formed. As shown in FIGS. 15 and 16, convex portions 308c and 308d are formed on the magnetic pole portions 308a and 308b of the stator 308 so as to narrow the gap between them in the direction opposite to each other. Similarly, the magnetic pole portions 309a, 3a of the stator 309 are
The convex portions 309c and 309d are formed on the 09b so as to narrow the gap between them in the direction opposite to each other. More specifically, the protrusions 308c, 308d,
309c and 309d are the magnetic pole portions 3 in plan view.
08a, 308b, 309a and 309b are rotors 307
Is formed along the shape opposite to, that is, the entire width.

Reference numeral 304 denotes a rotor shaft which is a rotary shaft fixed concentrically inside the cylinder of the rotor 307. The rotor shaft 304 is provided on the base plates 302 and 303 and is part 304b, 3b.
It is rotatably attached at 04c. The rotor shaft 3
A gear portion 304d is provided at 04, and the gear portion 304 is connected to a lens barrel feeding mechanism (not shown), a shutter drive mechanism (not shown), and the like, so that these can be driven. There is. Note that reference numerals 305 and 306 indicate coils for exciting the stators 308 and 309.

According to the above configuration, the coils 305, 30
Most of the magnetic flux generated in the stator due to the energization of 6 flows between the vicinity of the convex portion 308c and the convex portion 308d in which the air gap is narrowed, and between the vicinity of the convex portion 309c and the convex portion 309d. It is possible to prevent the leakage of the magnetic flux passing through and away from the magnetized portion of the rotor 307, and to efficiently apply the magnetic flux to the magnetized portion of the rotor 307, and as a result, it is possible to increase the motor output.

(Fifth Embodiment) FIG. 17 is a sectional view of a step motor according to a fifth embodiment. In the configuration of the step motor according to the fifth embodiment, the shapes other than the shape of the stator are the same as those in the fourth embodiment, and therefore the description of the other parts will be omitted and the stator will be described below. FIG. 17
As shown in FIG. 4, the stators 408 and 409 have a vertical gap L between the magnetic pole portions near the position facing the rotor.
_The shape is narrowed from ₁ to L ₂ (L ₁ > L ₂ ). As a result, as in the fourth embodiment, the magnetic flux generated by energizing the coils 305 and 306 causes the magnetic flux to be generated in the stators 408 and 409.
Come and go at a point where the upper and lower intervals of L are narrowed to L _1.
It becomes easy to act on the magnetic flux generated from the permanent magnet part 07, and the motor output can be increased.

(Sixth Embodiment) FIGS. 18 and 19 are a perspective view and a sectional view of a step motor according to a sixth embodiment. This step motor is a step motor of the same type as the step motor described in the first, fourth, and fifth embodiments. 18 and 19
In FIG. 5, reference numerals 508 and 509 respectively denote a first magnetizing ring and a second magnetizing ring made of permanent magnets. In these magnetizing rings, the magnetizing portion 507a serves as the S pole and the magnetizing portion 507b serves as the N pole. The magnetized portion 508a is magnetized so that it becomes the N pole and the magnetized portion 508b becomes the S pole. Reference numeral 504 denotes a rotor shaft, which is rotatably attached to the main plates 502 and 503 by portions 504b and 504c. A first magnetized ring 508 and a second magnetized ring 509 are fixed to the portion 504a of the rotor shaft 504 in such a manner that the polarities of the magnetized portions adjacent to each other above and below the first magnetized ring 508 and the magnetized portion 509 are different. The rotor shaft 504 has a gear portion 50.
4d is provided, and a lens barrel feeding mechanism (not shown) and a shutter driving mechanism (not shown) are connected to the gear portion 504d, and these mechanisms are driven by the rotor shaft 504. ing.

In such a stepping motor, the magnetic flux generated by energizing the coil between the magnetic pole portions 509b and 510b which are close to the magnetic path of the coil and the magnetic pole portions 509a and 510a which are far from the coil is in the magnetic path. The magnetic flux generated from the magnetic pole portions 509b and 510b near the coil due to leakage is closer to the magnetic pole portions 509a and 51 that are farther from the coil.
More than that generated from 0a.

Magnetic pole portions 509b, 51 near the coil
0b is opposed to the second magnetized ring and the first magnetized ring opposed to the magnetic poles 509a510a located away from the coil has the same residual magnetic flux. The output of the step motor does not rise because the magnetic flux generated when the coil is energized is not balanced. In order to increase the output of the step motor, it is necessary to make the magnetic flux generated by the permanent magnet, the magnetic flux generated in the magnetic pole portion by energizing the coil, and the magnetic flux generated in the magnetic pole portion by energizing the coil to be approximately the same amount.

The first magnetizing ring 507 is composed of a permanent magnet that produces less magnetic flux than that of the second magnetizing ring 508. For example, the second magnetizing ring 50
If 8 is a sintered magnet using a rare earth, the first magnetizing ring 507 is composed of a ferrite magnet or a plastic magnet.

With the above-mentioned structure, the magnetic layers 508a and 509a, which generate less magnetic flux when the coils 505 and 506 are energized, face the magnetized layer made of permanent magnets, which generate less magnetic flux. A magnetizing layer made of a permanent magnet having a large amount of magnetic flux generated by itself is opposed to the magnetic pole portions 508b and 509b having a large amount of magnetic flux generated by energizing the coil, thereby improving the output and efficiency of the step motor.

(Seventh Embodiment) FIG. 20 is a sectional view of a step motor according to a seventh embodiment. The seventh embodiment is substantially the same as the sixth embodiment except that the configuration of the permanent magnet is different. Therefore, the permanent magnet will be mainly described, and the other points will not be described. In this embodiment, a plurality of magnetized layers of the rotor are composed of the same permanent magnet 608.
No. 08 magnetized portions 608a and 608b and a magnetized layer formed of magnetized portions 608c and 608d have different magnetizing strengths at the time of magnetization, and the residual magnetic fluxes are different even though they are magnets of the same material. Has become. As a result, Example 6
The same effect as can be obtained.

(Embodiment 8) FIG. 21 is a sectional view of a step motor according to Embodiment 8. The eighth embodiment is substantially the same as the sixth embodiment except that the configuration of the permanent magnet is also different. Therefore, the permanent magnet will be mainly described, and the other points will not be described. In this embodiment, a plurality of magnetized layers of the rotor are composed of the same permanent magnet 708. However, from the first magnetized layer composed of magnetized portions 708a and 708b and the magnetized portions 708c and 708d. The inner diameters of the second magnetizing layers are different. That is, the first
The inner diameter D ₁ of the magnetizing layer and the inner diameter D ₂ of the second magnetizing layer are D ₁ > D
There is a relationship of ₂ . Since the outer diameter dimensions D ₀ are the same, the thickness of the magnet of each magnetized layer is (D ₀ −D ₁ ) / 2 <(D ₀ −D ₂ ) / 2, the permeance coefficient of the second magnetized layer is first
Magnetic flux φ _{2 that} is larger than the magnetized layer and is generated by the second magnetized layer
And the magnetic flux φ ₁ generated by the first magnetized layer have a relation of φ ₁ <φ ₂ , and the same effect as that of the sixth embodiment can be obtained.

[0047]

As described above, according to the present invention,
In the lens driving device, since the guide portion and the male screw portion are formed concentrically on the guide shaft fixed to the lens frame, the force for driving the lens frame in the optical axis direction acts at a position different from the guide portion. Therefore, it is possible to prevent the driving load from increasing due to the inclination of the lens frame, that is, the lens frame or the bending of the lens frame, and the increase in friction of the guide portion. Also, the planar shape of the lens barrel can be made compact.

Further, according to the present invention, in the step motor, the interval in the vicinity of the magnetic pole portion of the stator configured to have the upper and lower magnetic pole portions corresponding to the magnetized portion of the rotor is narrowed. The magnetic flux generated by the energization of the magnetic field passes near the rotor, and the magnetic flux generated from the permanent magnet of the rotor easily interacts with the magnetic flux to increase the output of the motor.

Further, according to the present invention, in the step motor, the magnetized layer of the permanent magnet facing the magnetic pole farther from the coil than the magnetic flux generated by the magnetized layer of the permanent magnet facing the magnetic pole closer to the coil is generated. Since the magnetic flux is configured to be small, the magnetic flux generated in the magnetic pole portion of the stator and the magnetic flux generated from the permanent magnet due to the energization of the coil are balanced, and the output and efficiency of the step motor can be increased.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of main components of the entire lens driving device according to a first exemplary embodiment.

FIG. 2 is a sectional view of a lens driving device.

FIG. 3 is a plan view of a lens driving device.

FIG. 4 is a perspective view of a step motor unit of the lens driving device.

FIG. 5 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a step motor used in a lens driving device.

FIG. 6 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a step motor used in a lens driving device.

FIG. 7 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a step motor used in a lens driving device.

FIG. 8 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a step motor used in a lens driving device.

FIG. 9 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a step motor used in a lens driving device.

FIG. 10 is a plan view showing a magnetized state of a stator at each rotational position of a rotor of a step motor used in a lens driving device.

FIG. 11 is a plan view showing the excited state of the suiter at each rotational position of the rotor of the step motor used in the lens driving device.

FIG. 12 is a plan view showing the excited state of the suiter at each rotational position of the rotor of the step motor used in the lens driving device.

FIG. 13 is a sectional view of a lens driving device according to a second embodiment.

FIG. 14 is a plan view of a step motor according to a third embodiment.

FIG. 15 is a perspective view of a step motor according to a fourth embodiment.

FIG. 16 is a sectional view of a step motor according to a fourth embodiment.

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

FIG. 18 is a perspective view of a step motor according to a sixth embodiment.

FIG. 19 is a sectional view of a step motor according to a sixth embodiment.

FIG. 20 is a sectional view of a step motor according to a seventh embodiment.

FIG. 21 is a sectional view of a step motor according to an eighth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main plate 2 Guide tube 3 Guide shaft 3b Male part 3a Fitting part 4 Rear group lens barrel 5 Coil 6 Coil 7 Rotor 7f Female thread portion 8 First stator 9 Second stator 10 Front group lens barrel 11 Compression spring 12 Steel ball 7f Female thread Part 107 Drive gear 108 Pinion gear 109 Motor 207 Rotor 208 First stator 209 Second stator 205 Coil 206 Coil 307 Rotor 308 Stator 309 Stator 408 Stator 409 Stator 507 Permanent magnet magnetized layer 508 Permanent magnet magnetized layer 509 Stator 510 Stator 608 rotor 609 stator 610 stator 708 rotor 709 stator 710 stator

Claims (17)

[Claims] 1. A guide shaft in which a male screw portion integrally formed with or fixed to a lens or a lens frame and a guide portion are coaxially formed, and a female screw portion engaging with the male screw portion of the guide shaft is formed. A lens driving device, comprising: a rotation driving body; and a base plate formed with a guide means that is fitted to the guide portion of the guide shaft and slidably supports the guide shaft in the axial direction. 2. The lens driving device according to claim 1, wherein the rotation driving body is a rotor of a step motor. 3. The lens driving device according to claim 2, wherein the rotor is a cylindrical rotor composed of permanent magnets having different poles magnetized alternately on the circumference, and the step motor is attached to the rotor. A lens driving device comprising: a plurality of stators each having a first magnetic pole portion and a second magnetic pole portion facing the magnetic portion; and a coil for exciting each of the stators. 4. The lens driving device according to claim 3, wherein the rotor has a plurality of magnetized layers formed in an axial direction thereof, and each magnetized layer has at least two magnetized portions and is adjacent to each other. The magnetic poles of each magnetized layer are magnetized with opposite polarities,
The first magnetic pole portion and the second magnetic pole portion of each of the stators are arranged so as to face magnetized portions of different magnetized layers in the axial direction of the rotor. 5. The lens driving device according to claim 3, wherein the rotor has four magnetized portions on its circumference, and the plurality of stators have magnetic pole portions facing the four magnetized portions. Characteristic lens drive device. 6. The lens drive device according to claim 1, wherein the rotary drive body is composed of a drive gear, and the drive gear is driven by a motor via a power transmission means. 7. A cylindrical rotor composed of permanent magnets magnetized in the radial direction, and a plurality of stators having a first magnetic pole portion and a second magnetic pole portion arranged facing the outer circumference of the rotor. A step motor having coils arranged to excite each of the stators, the rotor has a plurality of magnetized layers formed in its axial direction, and each magnetized layer has at least two magnetized portions. And the adjacent magnetic pole portions of each magnetized phase are magnetized to have opposite polarities, and the first magnetic pole portion and the second magnetic pole portion of each of the stators are different from each other in the axial direction of the rotor. A step motor, which is arranged so as to face a magnetized portion of a magnetic layer, and a gap between a first magnetic pole portion and a second magnetic pole portion near each magnetic pole portion of each stator is narrowed. 8. The step motor according to claim 7, wherein the first magnetic pole portion and the second magnetic pole portion in the vicinity of the magnetic pole portion of each stator are formed by forming convex portions inside the magnetic pole portions of each stator which face each other. Step motor characterized by narrowing the interval between. 9. The step motor according to claim 7, wherein the magnetic pole portions of the respective stators are deformed so as to face each other so that the gap between the first magnetic pole portion and the second magnetic pole portion near the magnetic pole portions of the respective stators. Step motor characterized by narrowing. 10. A plurality of rotors, each of which has a cylindrical shape and is made of a permanent magnet magnetized in a radial direction, and a plurality of first magnetic pole portions and second magnetic pole portions which are arranged so as to face the outer circumference of the rotor. A step motor having a stator and a coil arranged to excite each of the stators, the rotor has a plurality of magnetized layers formed in an axial direction thereof,
Each magnetized layer has at least two magnetized parts, and the magnetic pole parts of adjacent magnetized layers are magnetized to have opposite polarities, and the first magnetic pole part and the second magnetic pole of each of the stators are magnetized. Is disposed so as to face the magnetized portions of different magnetized layers in the axial direction of the rotor, and the magnetic flux generated by one magnetized layer is less than the magnetic flux generated by the other magnetized layer. A stepping motor having the following structure. 11. The step motor according to claim 10, wherein one magnetized layer is made of a permanent magnet different from the other magnetized layers. 12. The step motor according to claim 10, wherein one magnetized layer has a magnetizing strength different from that of the other magnetized layers. 13. The step motor according to claim 10, wherein one magnetized layer has an inner diameter different from that of the other magnetized layer. 14. The step motor according to claim 10, wherein the first magnetic pole portion of each of the stators is arranged closer to the coil with respect to the second magnetic pole portion, and each of the first magnetic pole portions of the rotor is arranged in the rotor. The second magnetic pole portion of each of the stators is arranged so as to face the magnetized portion of the first magnetized layer which is the same magnetized layer among the plurality of magnetized layers, and Are arranged so as to face different magnetized portions of the second magnetized layer, and the magnetic flux generated by the magnetized portion of the second magnetized layer is greater than the magnetic flux generated by the magnetized portion of the first magnetized layer. A step motor characterized by being configured so as to reduce the number thereof. 15. The step motor according to claim 14, wherein the first magnetizing layer and the second magnetizing layer are made of different permanent magnets. 16. The step motor according to claim 14, wherein the first magnetizing layer and the second magnetizing layer have different magnetizing strengths. 17. The step motor according to claim 14, wherein the first magnetizing layer and the second magnetizing layer have different inner diameter dimensions.