JP2001142110A - Electromagnetic actuator, shutter device and diaphragm device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic actuator suitable as a drive source of a shutter device having both of a shutter mechanism and a diaphragm mechanism and a diaphragm device whose diaphragm diameter can be controlled in multistage. SOLUTION: This electromagnetic actuator is provided with a rotor 2 which can be bidirectionally turned between one end position B and the other end position C across an intermediate position A and which is magnetized to two polarities, a horseshoe yoke 3 arranged at a position where magnetic attraction force is generated when the rotor 2 magnetized to two polarities is set at the position B and the position C, a coil 4 wound round the yoke 3 so as to turn the rotor 2 according as it is energized, and a self holding means for holding the rotor 2 at the position A, the position B or the position C in a non-energizing state in which the coil 4 is not energized. The self holding means is provided with an elastic member 5 regulating the rotor 2 at the position A by mechanical elastic force, one regulation member 41 regulating the rotor 2 at the position B by utilizing the magnetic attraction force generated between the yoke 3 and the other regulation member 42 regulating the rotor 2 at the position C by utilizing the magnetic attraction force generated between the yoke 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shutter device and a diaphragm device incorporated in a digital camera or the like.
Further, the present invention relates to an electromagnetic actuator used as a drive source of a shutter device and a diaphragm device.

[0002]

2. Description of the Related Art When photographing a subject using a camera, there is a case where it is desired to optimize a combination of a lens aperture and a shutter speed according to the situation. Conventionally, as such a camera, there has been a method in which a diaphragm mechanism for defining the aperture of a lens opening and a shutter mechanism for opening and closing the lens opening are separately provided and individually controlled. In such a diaphragm mechanism, the aperture of the lens aperture is generally defined in two stages.

[0003]

However, an electromagnetic actuator is required for driving the aperture mechanism and the shutter mechanism, respectively, and there are great restrictions in terms of cost and space efficiency. Also, as for the aperture mechanism, a system capable of setting the aperture in more stages is desired.

[0004] In view of such problems of the prior art, an object of the present invention is to provide a shutter device having both a shutter mechanism and an aperture mechanism. It is another object of the present invention to provide a diaphragm device capable of controlling the diaphragm diameter in more stages. It is another object of the present invention to provide an electromagnetic actuator suitable as a drive source for these shutter devices and aperture devices.

[0005]

The following means have been taken in order to achieve the above-mentioned object of the present invention. That is, the electromagnetic actuator according to the present invention includes a two-pole magnetized rotor capable of bidirectional rotation between one end position and the other end position with the intermediate position interposed therebetween, and the two-pole magnetized rotor. A horseshoe-shaped yoke arranged at a position where a magnetic attraction force is generated at the one end position and the other end position, a coil wound around the yoke to rotate the rotor in accordance with energization, and energizing the coil. Self-holding means for holding the rotor at an intermediate position, one end position or the other end position in a non-energized state. The self-holding means includes: an elastic member that regulates the rotor to an intermediate position by mechanical elastic force; and an elastic member that regulates the rotor to one end position by using a magnetic attractive force generated between the yoke and the elastic member. And the other regulating member that regulates the rotor to the other end position by utilizing a magnetic attraction force generated between the yoke and the yoke. Specifically, the rotor is
When it reaches the intermediate position, the elastic force overcomes the suction force and is regulated to the intermediate position. When it reaches the one end position, the suction force overcomes the elastic force and is held at the one end position. When this occurs, the suction force overcomes the elastic force and is held at the other end position. Further, the coil requires a larger amount of current when driving the rotor from the intermediate position to one end position or the other end position than when driving the rotor from one end position or the other end position to the intermediate position.

According to the present invention, there is further provided a shutter blade disposed on a substrate having a lens opening for opening and closing the lens opening.
An electromagnetic actuator that is connected to the shutter blades and drives the shutter blades to open and close. The electromagnetic actuator is bipolarly magnetized so as to be bidirectionally rotatable between one end position and the other end position across an intermediate position. And a horseshoe-shaped yoke arranged at a position where magnetic attraction is generated when the two-polarized rotor is at one end position and the other end position. And a self-holding means for selectively holding the rotor at three points: an intermediate position, one end position, and the other end position in a non-energized state in which the coil is not energized. In the shutter device provided, the self-holding means uses an elastic member that regulates the rotor to an intermediate position with a mechanical elastic force and a magnetic attraction force generated between the yoke and the rotor, and the self-holding means uses the magnetic attractive force. One regulation that regulates to one end position And the other restricting member that restricts the rotor to the other end position by using a magnetic attraction force generated between the yoke and the yoke. The shutter blade can be held by the self-holding means. According to the three points of the rotor,
It is possible to shift to three points: a fully open position for opening the lens opening, a fully closed position for closing the lens opening, and a half open position for partially opening the lens opening. In one aspect, the shutter blade is located at a half-open position corresponding to one end position of the rotor, at a fully closed position corresponding to an intermediate position of the rotor, and at a fully open position corresponding to the other end position of the rotor. Is placed. In another aspect, the shutter blade is located at a fully closed position corresponding to one end position of the rotor, is located at a half open position corresponding to an intermediate position of the rotor, and is at a fully open position corresponding to the other end position of the rotor. To be placed.

The present invention further comprises an aperture blade disposed on a substrate having a lens opening for regulating the aperture of the lens aperture, and an electromagnetic actuator connected to and driving the aperture blade. Is a bipolar-polarized rotor rotatable bidirectionally between one end position and the other end position across the intermediate position, and the bipolar-polarized rotor is at one end position and the other end position. A horseshoe-shaped yoke arranged at a position where a magnetic attraction force occurs, and a coil wound around the yoke to rotate the rotor in accordance with energization,
A self-holding means for selectively holding the rotor at three positions of an intermediate position, one end position, and the other end position in a non-energized state in which the coil is not energized; An elastic member that regulates the rotor to an intermediate position by mechanical elastic force, and one regulating member that regulates the rotor to one end position by using a magnetic attraction force generated between the yoke and the elastic member. And the other restricting member that restricts the rotor to the other end position by utilizing a magnetic attraction force generated between the yoke and the rotor, wherein the diaphragm blade can be held by the self-holding means. According to the three points, the aperture of the lens aperture can be set to three points that can be regulated so as to be different from large, medium and small.

The electromagnetic actuator according to the present invention includes a self-holding means, and is capable of self-holding the rotor at one of the one end position, the other end position, and an intermediate position therebetween without energization. The one end position and the other end position are located at both extremes of the operating angle of the rotor. By incorporating such an electromagnetic actuator as a drive source of the shutter device, the shutter blades correspond to the three points of the self-held rotor, and are fully opened,
It can be shifted to three points, fully closed position and half open position. By using the half-open position as the small aperture state, this shutter device has a two-stage aperture configuration of the full-open position or the half-open position, and a single electromagnetic actuator can drive the shutter device that combines the shutter mechanism and the aperture mechanism. become. Also, by incorporating the present electromagnetic actuator into the diaphragm device, the diaphragm blades can be set at three points where the aperture of the lens opening can be regulated differently from large, medium and small according to the three points of the rotor that can be held by itself. It is possible to realize stepwise aperture setting.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration and operation of the electromagnetic actuator according to the present invention.
As shown in FIG. 1A, the present electromagnetic actuator is composed of a rotor 2 polarized in two poles, a horseshoe-shaped yoke 3, and a coil 4 wound therearound. The rotor 2 has a rotating shaft 2b, and can rotate bidirectionally between one end position and the other end position with the intermediate position shown in FIG. In FIG. 1, one end position is shown in (B) and the other end position is shown in (C).
The horseshoe-shaped yoke 3 is arranged at a position where magnetic attraction is generated when the two-pole magnetized rotor 2 is at one end position (B) and the other end position (C). The coil 4 wound around the yoke 3 rotates the rotor 2 bidirectionally in response to energization from a drive circuit (not shown). As a characteristic feature, the present electromagnetic actuator is provided with self-holding means, and when the coil 4 is not energized, the bipolar magnetized rotor 2 is moved to the intermediate position (A), one end position (B) or the other end position. (C). More specifically, the self-holding means uses a magnetic attraction force generated between the elastic member 5 for restricting the rotor 2 to the intermediate position (A) by a mechanical elastic force and the yoke 3 and the rotor 2.
And the other regulating member that regulates the rotor 2 to the other end position (C) by using the magnetic attraction force generated between the yoke 3 and the other end position (C). Consists of The elastic member 5 is composed of a coil spring having a pair of open ends, and is fixed to a fixing pin 1b planted on a main plate (not shown). Both open ends of the elastic member 5 are engaged with a small-diameter portion of an operating pin 2a that rotates integrally with the rotor 2,
The rotor 2 is held at the intermediate position (A) with a predetermined elastic force.
Note that the guide pin 1 is used to secure the stable operation of the elastic member 5.
c is interposed between the fixed pin 1b and the operating pin 2a.
When the rotor 2 is at the one end position (B), the regulating member 41 abuts on the large diameter portion of the operating pin 2a to regulate its clockwise rotation, thereby holding the rotor 2 by itself. The rotor 2 attempts to rotate clockwise due to the attraction force generated between the rotor 2 and one end of the yoke 3 even in a non-energized state, but its movement is regulated by the regulating member 41. As a result, the one end position (B )
Will be self-held. Similarly, the other end position (C)
, The large-diameter portion of the operating pin 2a of the rotor 2 comes into contact with the other regulating member 42 and is held by itself. In the present embodiment, when the rotor 2 comes to the intermediate position (A), the elastic force of the elastic member 5 exceeds the magnetic attractive force and is regulated to the intermediate position (A). Further, when it reaches the one end position (B), the magnetic attraction force exceeds the elastic force of the elastic member 5 and is held at the one end position (B). Similarly, when it comes to the other end position (C), the suction force between the yoke 3 and the rotor 2 overcomes the elastic force of the elastic member 5 and is held at the other end position (C) by itself. In this case, the coil 4 moves the rotor 2 from the intermediate position (A) to the one end position (B) as compared with the amount of current required when driving the rotor 2 from the one end position (B) or the other end position (C) to the intermediate position (A). ) Or other end position (C)
The amount of current required when driving the motor is large.

According to the present invention, at both extremes (one end position and the other end position) of the operating angle range of the rotor 2, the magnetic attraction force is applied between the bipolar magnetized rotor 2 and the horseshoe-shaped yoke 3. Are arranged so as to occur in a non-energized state. And
An elastic member 5 is provided at an intermediate position of the operating angle range of the rotor 2 so as to hold an operating pin 2a that rotates integrally with the rotor 2. At the extremes of the operating angle range of the rotor 2, self-holding is performed by the attractive force between the yoke 3 and the two-pole magnetized rotor 2, and the position is held by the elastic force of the elastic member 5 at the middle position of the operating angle range. Can be. In order to operate the rotor 2 from the one end position or the other end position to the intermediate position, the coil 4 wound around the yoke 3 may be energized.
In order to stop just at the intermediate position from the one end position or the other end position, the energization time or the applied voltage to the coil 4 may be controlled and the braking energization (brake energization) may be performed.

The operation of the electromagnetic actuator according to the present invention will be described with reference to FIG. The initial state is (A)
Thus, the rotor 2 is held just in the middle of the operating angle range. When the coil 4 is energized in the forward direction in this state,
As shown in (B), an N pole is generated at one end of the yoke 3, and the rotor 2 rotates clockwise by the magnetic force, and the regulating member (stopper)
Stops at 41. As described above, even if the current supply to the coil 4 is interrupted in this state, this state is maintained by the attractive force between the bipolar magnetized rotor 2 and the yoke 3. Next, when the coil 4 is energized in the reverse direction from the state shown in (B), an S pole is generated at one end of the yoke 3 and an N pole is generated at the other end as shown in (C). As a result, the bipolar-polarized rotor 2 rotates counterclockwise. At this time, the brake can be applied by controlling the energization time and switching the energization to the opposite polarity after a lapse of a predetermined time, or by controlling the applied voltage, and can be stopped at the intermediate position shown in (A). Since this state is the same as the initial state, the position can be maintained without energization. Further, by performing the reverse-direction energization from the initial state shown in (A), the rotor 2 can be rotated counterclockwise to shift to the other end position shown in (C). In this state, self-holding can be performed even when the energization is cut off, as in the case shown in FIG. By executing the forward direction energization while controlling it from the state shown in (C),
It is possible to return to the initial state of (A).

Next, a first embodiment of a shutter device incorporating the electromagnetic actuator shown in FIG. 1 will be described with reference to FIGS. FIG. 2 schematically shows a state where the rotor 2 of the electromagnetic actuator is at the intermediate position. This shutter device is assembled using a base plate (not shown). The electromagnetic actuator is located on the upper surface side of the main plate, and a pair of shutter blades 6 and 7 connected thereto are arranged on the lower surface side of the main plate. The operating pin 2a that moves integrally with the rotor 2 penetrates the main plate from the upper surface to the lower surface, and engages with long holes formed in the shutter blades 6 and 7, respectively. One shutter blade 6 is mounted so as to be rotatable around a pin planted on the lower surface side of the main plate. This pin is located just opposite to the rotor rotation shaft 2b disposed on the upper surface side of the main plate. Similarly, the other shutter blade 7 is mounted so as to be rotatable around a pin planted on the lower surface side of the main plate. This pin is located at substantially the same position as the guide pin 1c implanted on the upper surface side of the main plate.

A lens aperture 1a is formed in the base plate. When the rotor 2 is in the illustrated intermediate position, the operating pin 2a
The shutter blades 6, 7 interlocking with the rotor 2 through are located at the fully closed position where the lens opening 1a is completely closed.

When the coil 4 is energized in the forward direction from the fully closed position, the rotor 2 travels to one end position as shown in FIG. When the rotor 2 is at one end position, the shutter blades 6 and 7 interlocked with the rotor 2 rotate so as to approach each other, and an opening 6a formed in one of the shutter blades 6 is formed.
Then, the opening 7a formed in the other shutter blade 7 just overlaps on the lens opening 1a. As a result, the lens opening 1a is partially opened by the pair of shutter blades 6 and 7, and is placed in a half-open state.

Conversely, when the coil 4 is energized in the reverse direction from the state shown in FIG. 2, the rotor 2 rotates counterclockwise, and reaches the other end position shown in FIG. The pair of shutter blades 6 and 7 linked to the rotor 2 run in opposite directions, and completely open the lens opening 1a to be in a fully opened state.

As described above, in the present shutter device, the pair of shutter blades 6 and 7 are in the fully open position where the lens opening 1a is opened according to the three points of the rotor 2 which can be held by the self-holding means of the electromagnetic actuator. It is possible to shift to three points: a fully closed position for closing 1a, and a half-open position for partially opening lens opening 1a. In particular, in the present embodiment, the pair of shutter blades 6 and 7 are located at a half-open position corresponding to one end position of the rotor 2 (FIG. 3), and are located at a fully closed position corresponding to an intermediate position of the rotor 2 (FIG. 3). 2), the rotor 2 is placed at the fully open position (FIG. 4) corresponding to the other end position. When a shutter device performing such an operation is incorporated in a digital still camera, the shutter device is first set to the fully closed position in FIG. 2 and then to the half open position in FIG. 3 or the fully open position in FIG. The shutter blades 6 and 7 are set. Thereafter, the shutter blades 6, 7 are returned from the fully open position or the half open position to the fully closed position shown in FIG. 2 in response to the release button being pressed. When the shutter device is incorporated in a normal silver halide still camera, one of the half-open state in FIG. 3 and the fully-open state in FIG. 4 is selected in advance in accordance with subject luminance information. At the same time as the shutter release button is turned on, the energization of the coil 4 is controlled so that the pair of shutter blades 6, 7 travel from the fully closed position in FIG. 2 to a preselected half open position in FIG. 3 or a fully open position in FIG. The energization is switched to return from the half-open position or the fully-open position to the fully-closed position in FIG. Thus, one exposure operation is completed.

As described above, in this embodiment, the intermediate position is made to correspond to the fully closed position in the non-energized state of three points, and the one end position (start point)
Correspond to the half open position, and the other end position (end point) corresponds to the fully open position. In this case, in the digital still camera, since the shutter blades are set to the fully-open position or the half-open position in advance, if the current flowing through the coil of the electromagnetic actuator is increased, there is a possibility that the operation will not stop at the middle point from the start point but will end at the end point. . Complicated electrical control is required to suppress such malfunctions. Further, when switching between the half-open state and the fully-opened state in accordance with the luminance of the subject in the through state of the digital still camera, it is necessary to pass through the fully-closed state once, and control for that is required. Therefore, FIGS. 5 to 7 show a second embodiment for the purpose of simplifying the above control. Generally, the shutter blades in the second embodiment are located at the fully closed position corresponding to one end position (start point) of the rotor, and are located at an intermediate position (middle point) of the rotor.
Is placed at the half-open position, and is placed at the full-open position corresponding to the other end position (end point) of the rotor. Since it is set to be fully open at the end point and half-open at the middle point, the maximum current allowed by the rating can flow from each state to the fully closed state at the start point, so the closing time of the shutter blade is the second embodiment It can be shortened compared to. In addition, even in the through state, it is possible to switch between the fully open position and the half open position without going through the fully closed position. In either case, control is simplified.

FIG. 5 shows a state in which the rotor 2 is located at an intermediate position, and a pair of shutter blades 6 and 7 interlocked with the rotor 2 have a lens opening 1a.
Is placed at a position where the light is partially shielded, so that it is set at the half-open position. In the state shown in FIG. 6, the rotor 2 is self-supported at one end position, and a pair of shutter blades 6 and 7 interlocking with each other completely overlap the lens opening 1a. Therefore, the shutter blades 6, 7 are set at the fully closed position.
In the state shown in FIG. 7, the rotor 2 is self-held at the other end position, and a pair of shutter blades 6, 7
Are opposed to each other from the lens opening 1a. As a result, the shutter blades 6, 7 are set to the fully open position. When operating the shutter device having such a configuration, in the digital still camera, for example, the intermediate position is changed from the half-open state to the fully closed state by clockwise rotation. When setting to the fully open state, the power is supplied in the opposite direction and the motor rotates counterclockwise. In the fully-open state and the half-open state, non-energization is maintained, and by performing energization from the same state at the maximum rated current, operation to the fully closed state becomes possible.

FIGS. 8 to 10 are schematic plan views showing an embodiment of a diaphragm device incorporating the electromagnetic actuator according to the present invention. The basic configuration is the same as that of the above-described embodiment of the shutter device, and the corresponding portions are denoted by the corresponding reference numerals to facilitate understanding. In FIG. 8, the rotor 2 is held at an intermediate position by itself, and a pair of aperture blades 60 and 70 interlocked with the rotor 2 are set so that the aperture of the lens opening 1a has an intermediate diameter. In particular,
A first opening 61 formed in one of the diaphragm blades 60 and a first opening 71 formed in the other of the diaphragm blades 70 just overlap the lens opening 1a, and the size of the diaphragm becomes an intermediate diameter. . In the state shown in FIG. 9, the rotor 2 is self-held at one end position, and the aperture blade 6
Reference numerals 0 and 70 are set such that the aperture of the lens opening 1a has a minimum diameter. Specifically, the second opening 62 formed in the diaphragm blade 60 and the second opening 72 formed in the diaphragm blade 70 just overlap the lens opening 1a. Since the diameters of the openings 62 and 72 are smaller than the diameters of the openings 61 and 71, the aperture has the minimum diameter. The state shown in FIG. 10 is a case where the rotor 2 is self-held at the other end position, and the pair of aperture blades 60 and 70 interlocking with this is retracted to both sides from the lens opening 1a. Lens aperture 1a
Has no maximum aperture because it has no aperture.
As described above, the aperture blades 60 and 70 are provided with the lens aperture 1 according to the three points of the rotor 2 which can be held by the self-holding means.
The aperture of a can be set to three points that can be regulated differently from large, medium and small.

[0020]

As described above, according to the present invention,
By utilizing the elastic force of the elastic member and the attraction force of the magnetic yoke, the electromagnetic actuator can be self-held at three points. If this is incorporated in a shutter device, a camera shutter with two apertures can be realized. it can. Further, when the present electromagnetic actuator is incorporated in a diaphragm device, three stages of diaphragm states can be obtained with one actuator.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an electromagnetic actuator according to the present invention.

FIG. 2 is a plan view showing a first embodiment of the shutter device according to the present invention.

FIG. 3 is a plan view showing a first embodiment of the shutter device according to the present invention.

FIG. 4 is a plan view showing a first embodiment of the shutter device according to the present invention.

FIG. 5 is a plan view showing a second embodiment of the shutter device according to the present invention.

FIG. 6 is a plan view showing a second embodiment of the shutter device according to the present invention.

FIG. 7 is a plan view showing a second embodiment of the shutter device according to the present invention.

FIG. 8 is a plan view showing an embodiment of a diaphragm device according to the present invention.

FIG. 9 is a plan view showing an embodiment of a diaphragm device according to the present invention.

FIG. 10 is a plan view showing an embodiment of a diaphragm device according to the present invention.

[Explanation of symbols]

1a ... Lens opening, 1b ... Fixing pin, 1c ...
.Guide pin, 2 ... Rotor, 2a ... Operation pin, 2
b: rotating shaft, 3: yoke, 4: coil, 4
DESCRIPTION OF SYMBOLS 1 ... regulating member, 42 ... regulating member, 5 ... elastic member, 6 ... shutter blade, 7 ... shutter blade,
60 aperture blades, 70 aperture blades

Claims (7)

[Claims] 1. A two-pole magnetized rotor capable of bidirectional rotation between one end position and the other end position with an intermediate position interposed therebetween, and the two-pole magnetized rotor having one end position and the other end. A horseshoe-shaped yoke arranged at a position where magnetic attraction is generated when in a position, a coil wound around the yoke to rotate the rotor in accordance with energization, and a non-energized state in which the coil is not energized In the intermediate position, self-holding means for holding the rotor at one end position or the other end position, the self-holding means, an elastic member for regulating the rotor to the intermediate position by mechanical elastic force, A regulating member that regulates the rotor at one end position by using a magnetic attraction force generated between the yoke and the rotor using a magnetic attraction force generated between the yoke and the rotor; And the other regulating member that regulates the other end position. Actuator. 2. When the rotor reaches an intermediate position, the elastic force overcomes the suction force and is restricted to the intermediate position. When the rotor reaches one end position, the attractive force overcomes the elastic force and the rotor moves to the one end position. 2. The electromagnetic actuator according to claim 1, wherein the suction force overcomes the elastic force and is held at the other end position when the other end position is reached. 3. The current supply amount required when driving the rotor from the intermediate position to one end position or the other end position is greater than the current supply amount required when driving the rotor from one end position or the other end position to the intermediate position. The electromagnetic actuator according to claim 1, wherein is larger. 4. A shutter blade disposed on a substrate having a lens opening for opening and closing the lens opening, and an electromagnetic actuator connected to the shutter blade for driving the shutter blade to open and close, wherein the electromagnetic actuator is located at an intermediate position. A two-pole magnetized rotor rotatable bidirectionally between one end position and the other end position, and a magnetic pole when the two-pole magnetized rotor is at one end position and the other end position. A horseshoe-shaped yoke arranged at a position where an attraction force is generated, a coil wound around the yoke to rotate the rotor in accordance with energization, and a non-energized state where the coil is not energized. A self-holding means for selectively holding at three points of an intermediate position, one end position and the other end position, wherein the self-holding means regulates the rotor to an intermediate position by mechanical elastic force. Elastic part And one of the regulating members that regulates the rotor to one end position using magnetic attraction force generated between the yoke and the magnetic attraction force generated between the yoke and the yoke. The shutter blade has a full-open position to open the lens opening in accordance with three points of the rotor that can be held by the self-holding means; And a half-open position in which the lens opening is partially opened. 5. The shutter blade is located at a half-open position corresponding to one end position of the rotor, at a fully closed position corresponding to an intermediate position of the rotor, and at a fully open position corresponding to the other end position of the rotor. 5. The shutter device according to claim 4, wherein the shutter device is disposed. 6. The shutter blade is located at a fully closed position corresponding to one end position of the rotor, at a half open position corresponding to an intermediate position of the rotor, and at a fully open position corresponding to the other end position of the rotor. 5. The shutter device according to claim 4, wherein the shutter device is disposed. 7. An aperture blade disposed on a substrate having a lens opening and regulating an aperture of the lens aperture, and an electromagnetic actuator connected to and driving the aperture blade, wherein the electromagnetic actuator is an intermediate member. A two-pole magnetized rotor rotatable bidirectionally between one end position and the other end position, and a magnetic pole when the two-pole magnetized rotor is at one end position and the other end position. A horseshoe-shaped yoke disposed at a position where a strong suction force is generated, a coil wound around the yoke to rotate the rotor in accordance with energization, and the rotor in a non-energized state in which the coil is not energized. A self-holding means for selectively holding the rotor at three points of an intermediate position, one end position and the other end position, wherein the self-holding means moves the rotor to the intermediate position by mechanical elastic force. An elastic member for regulating, And a restricting member that regulates the rotor to one end position by using a magnetic attraction force generated between the yoke and the yoke. The other end of the aperture blade is restricted to the other end position, and the aperture blade can regulate the aperture of the lens opening to be different from large, medium and small in accordance with three points of the rotor which can be held by the self-holding means. An aperture device which can be set to three different points.