JPH10254022A - Motor driven diaphragm device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance producing efficiency by facilitating assembling work and reducing the number of parts and to optionally hold a diaphragm blade on the maximum diaphragm side or on the minimum diaphragm side in a non conductive state. SOLUTION: This device is provided with the diaphragm blades 40 and 50 adjusting the size of an aperture part for photographing light and a motor 90 driving the blades 40 and 50 between the minimum diaphragm position and the maximum diaphragm position. Then, the motor 90 is constituted of a rotor 93 provided with a permanent magnet 93a and engaged with the blades 40 and 50 and a stator provided with coils 98 and 99 arranged at the outside circumference of the rotor 93 and set for giving rotational force to the rotor 93 by energizing the coils 98 and 99. Besides, a magnetic piece 101 generating attraction force between the N pole or the S pole of the magnet 93a and giving rotational pressing force to the rotor 93 when the blades 40 and 50 are operated to an intermediate position between the minimum diaphragm position and the maximum diaphragm position is arranged at a position being equally distant from the N pole and the S pole which are mutually adjacent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorized aperture device mounted on a photographing device such as a video camera.

[0002]

2. Description of the Related Art FIG. 7 is an exploded perspective view showing an example of a conventional electric diaphragm device.

[0003] In the figure, reference numeral 10 denotes a ground plane, and 20 denotes a ground plane.
A motor for driving the diaphragm blades, which is attached to one surface (the upper surface in FIG. 7), is disposed on the other surface (the lower surface in FIG. 7) of the main plate 10 and has a rotor shaft of the motor 20. The aperture blade drive levers 40 and 50 which are connected to 23 and are rotated in the directions of the arrows (a) or (b) are locked at both ends of the aperture blade drive lever 30, respectively, in accordance with the rotation of the lever 30. A pair of diaphragm blades 60, which are slid linearly in the direction of arrow f1 and arrow f2, are screwed to the other surface of the base plate 10 (ie, the lower surface in FIG. 7), and the diaphragm blades 40 and 50 are screwed. Cover, 7
0 is N bonded to one end of the opening of one of the diaphragm blades 40.
It is a D filter.

The base plate 10 is integrally formed by injection molding of plastic and has an opening 1 through which photographing light passes.
1, a yoke support seat 12, and two bearing mounting columns 13, 1
4 is provided. Here, the yoke support seat 12
Is provided for supporting a cylindrical yoke 21 for mounting the motor, and is cylindrically projected at a position slightly away from the opening 11. The yoke support seat 12
A shaft hole 15 for rotatably supporting a rotor shaft 23 of the motor 20 is provided at a position which is a center of the yoke support seat 12 on the inner side of the bottom plate surface. It is made to protrude below the main plate 10 through the shaft hole 15.

In addition, the two bearing mounting columns 13, 14
Is for fixing the bearing plate 22 of the motor 20, protrudes from the inside of the yoke support seat 12, and has a screw hole 13 a for a screw B 1 for fixing the bearing plate 22 at each end surface. 14a are formed.

Further, boss portions 1 are provided on both side edges of the base plate 10.
The bosses 16 and 17 have screw holes 16 a and 17 penetrating in the direction of the thick plate of the base plate 10.
a is provided. These screw holes 16a, 17a are for screwing the cover 60 to the base plate 10, and the cover 60 is provided with ear pieces 61, 62 to be brought into contact with the bosses 16, 17, and these ears are provided. Pieces 61, 62
Are provided with holes 61a and 62a through which screws B2 screwed into the screw holes 16a and 17a are inserted.

A hole 63 is provided at one end (right end in FIG. 7) of the cover 60. The hole 63 corresponds to a screw hole (not shown) provided on the lower surface of the base plate 10 and is for screwing one end of the cover 60 to the base plate 10 with a screw B3.

The aperture blade drive lever 30 has a boss 31 with a hole at the center thereof, and the aperture blade 40 at both ends.
It has pins 32 and 33 to be engaged with 50. The tip of the rotor shaft 23 protruding from the rotor 24 is fitted in the hole 34 of the boss 31 having the hole. In this case, the rotor shaft 23 is fitted in a state where the positions of the pins 32 and 33 of the lever 30 are positioned with respect to the magnetic pole direction (the directions of the arrows N and S) of the rotor 24. One pin 32 of the diaphragm blade drive lever 30 is slidably inserted into a lateral groove 51 of one diaphragm blade 50, and the other pin 33 slides into a lateral groove 41 of the other diaphragm blade 40. It is movably inserted. Also, the boss 3 with a hole of the aperture blade drive lever 30 is provided.
1 is provided with a torsion spring 35 for constantly biasing the aperture blade drive lever 30 in one direction (the aperture cutting direction = the initial position direction of the aperture blades 40 and 50).

The aperture blades 40 and 50 have long grooves 42, 43, 44, 52, 53 and 5 in parallel with their respective side edges.
4 are provided, and these long grooves 42, 43, 4
Guide pins (not shown) projecting from the lower surface of the base plate 10 are inserted into the holes 4, 52, 53, and 54.

The motor 20 includes a permanent magnet rotor 24 having rotor shafts 23 and 29, a pair of coil bobbins 25 and 26 opposed to each other with the rotor 24 interposed therebetween so as to surround the rotor 24. Each coil bobbin 2
Coils 27 and 28 wound around coils 5 and 26, a cylindrical yoke 21 which is set on the yoke support seat 12 of the base plate 10 and surrounds the coil bobbins 25 and 26; 14 and a bearing plate 22 which is screwed to the distal end.

In the rotor 24, the rotor shaft 23 and the rotor shaft 29 projecting from both ends are on the same axis, and one rotor shaft 23 is inserted through the shaft hole 15 of the base plate 10,
The hole 34 of the boss 31 with the hole of the aperture blade drive lever 30
Is tightly fitted. Also, the other rotor shaft 29
Are rotatably supported in bearing holes 22a of the bearing plate 22.

The bearing plate 22 is electrically connected to both ends of one of the coils 27 and protrudes upward from the upper surface of the coil bobbin 25, in addition to the bearing hole 22a for rotatably supporting the rotor shaft 29. Notches 22f for inserting the terminals 27a and 27b formed therein, and holes 22 for electrically connecting the both ends of the other coil 28 and for inserting the terminals 28a and 28b projecting upward from the upper surface of the coil bobbin 26.
d, 22e, and holes 22b through which screws B1 screwed into screw holes 13a, 14a at the tips of the bearing mounting columns 13, 14 are passed.
22c, and are fixed to the distal ends of the bearing mounting columns 13, 14 by two screws B1.

[0013]

The above-mentioned conventional electric throttle device has the following problems.

That is, since the aperture blade drive lever 30 is urged in one direction (the aperture cutting direction) by the torsion spring 35,
When the power supply to the motor 20 is stopped, the aperture blade 4
0 and 50 are held at the aperture stop position (maximum aperture position). Therefore, even if there is a request to hold the aperture blades 40 and 50 on the open side (minimum aperture side), it was not possible to cope with the request in the non-energized state. In order to cope with this, it is necessary to keep the motor energized so that the aperture blade operates on the open side, and this causes a problem that the current consumption increases and the life of the battery power source is shortened. Further, when the urging force is obtained by the spring as in the related art, there is a trouble in assembling the spring.

In the conventional electric throttle device, the motor 2
0 and the diaphragm blade drive lever 30 are separate bodies, and the tip of the rotor shaft 23 is
It has to be fitted in the hole 34 of the aperture blade drive lever 30. Moreover, at that time, the direction of the magnetic pole of the permanent magnet (arrows N, S
Direction) and the direction of the aperture blade drive lever 30 are precisely aligned, and then the tip of the rotor shaft 23 is not fitted into the hole 34 of the aperture blade drive lever 30 so as not to slip and come off. must not. For this reason, the number of parts increases, and the assembling is very troublesome, which causes deterioration of production efficiency.

Therefore, the present invention aims to improve production efficiency by facilitating assembly and reducing the number of parts, and to enable the diaphragm blade to be arbitrarily held at the maximum diaphragm side or the minimum diaphragm side in a non-energized state. Is a problem to be solved.

[0017]

According to a first aspect of the present invention, there is provided an aperture blade for adjusting the size of an aperture for photographing light, and a motor for driving the aperture blade between a minimum aperture position and a maximum aperture position. Wherein the motor comprises a rotor having a permanent magnet and engaged with the aperture blades, and a stator having a coil arranged on the outer periphery of the rotor and energizing the coil to apply a rotational force to the rotor. When the diaphragm blade is operated to an intermediate position between the minimum diaphragm position and the maximum diaphragm position, the N pole or the S pole is located at a position equidistant from the mutually adjacent N pole and S pole of the permanent magnet. A magnetic piece that generates an attractive force between the poles and thereby applies a rotational urging force to the rotor is provided.

In this device, the magnetic pole of the rotor near the magnetic piece is attracted to the magnetic piece when the power supply is stopped. Therefore, the aperture blade can be arbitrarily held at either the maximum aperture position or the minimum aperture position depending on the position where the power supply is stopped. When the diaphragm blade is moved, the coil is energized to move the rotor. In this case, the energizing direction of the rotor changes at an intermediate opening of the diaphragm blade. Therefore, by controlling the energization based on the position of the intermediate opening, the aperture can be adjusted to an arbitrary opening. At this time, since the origin of the urging force is located at the position of the intermediate opening, the motor drive current required for aperture control can be reduced by half.

According to a second aspect of the present invention, there is provided a base plate having an opening for photographing light, an aperture blade which is slid linearly along the surface of the base plate to adjust the size of the opening, An electric diaphragm device comprising: a motor that drives an aperture blade; and an aperture blade drive lever that is disposed between a rotor shaft of the motor and the aperture blade and that converts a rotational motion of the rotor shaft into a linear motion of the aperture blade. The drive lever is formed integrally with the rotor shaft.

According to a third aspect of the present invention, there is provided a base plate having an opening for photographing light, a diaphragm blade which is slid linearly along the surface of the base plate to adjust the size of the opening, A motor for driving the aperture blade between a minimum aperture position and a maximum aperture position, an aperture blade drive lever disposed between the rotor shaft of the motor and the aperture blade, and for converting the rotational motion of the rotor shaft into linear motion of the aperture blade; Wherein the motor comprises: a rotor having a permanent magnet and the rotor shaft; and a stator having a coil disposed on the outer periphery of the rotor and a stator for applying a rotational force to the rotor by energizing the coil. In the apparatus, when the diaphragm blade is operated to an intermediate position between the minimum diaphragm position and the maximum diaphragm position, the N pole or the S pole is located at a position equidistant from the mutually adjacent N pole and S pole of the permanent magnet.
A magnetic piece for generating a suction force between the poles and thereby applying a rotational urging force to the rotor is provided, and the diaphragm blade drive lever is integrally formed with the rotor shaft.

[0021]

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

FIG. 1 is an exploded perspective view showing the structure of the electric diaphragm device. Note that, in the embodiment of the present invention, the same components as those of the conventional electric diaphragm device shown in FIG.

This electric diaphragm device includes a base plate 80, a motor 90 for driving a diaphragm blade mounted on the upper surface side of the base plate 80, and a diaphragm blade drive lever portion 30B which is locked to both ends of a diaphragm blade drive lever portion 30B. Arrow f according to the rotation of
Diaphragm blades 40 and 50 that slide linearly in one direction and the arrow f2 direction, a cover 60 attached to the lower surface side of the base plate 80 to cover the diaphragm blades 40 and 50, and one end of an opening of the diaphragm blade 40 And a DN filter 70 adhered to the first and second filters. In this case, the diaphragm blade drive lever portion 30B is resin-molded integrally with the rotor shaft 92 of the motor 90.

The base plate 80 is integrally formed by injection molding of plastic, and has an opening 81 through which photographing light passes.
And a pair of semicircular yoke support seats 82 and four hooks 83. The yoke support seat 82 is
For supporting the yoke 91, and protrudes from the opening 81 in a position slightly apart from each other. A shaft hole 85 is formed at a center position of the bridge 100 connecting and fixing the two yoke support seats 82, and the tip of the rotor shaft 92 of the motor 90 is inserted into the shaft hole 85 to be rotatably supported. ing. Around the shaft hole 85, bobbin positioning protrusions 86, 87 for positioning a coil bobbin (described later), which is a component of the motor 90, are provided.

The hook 83 is connected to the yoke 9 of the motor 90.
As shown in FIG. 5, in the thickness direction of the base plate 80 (that is, in the axial direction of the yoke 91 and the rotor shaft 92 assembled on the base plate 80), as shown in FIG. An extended shaft portion 83a, and a projection 83b protruding from an end of the shaft portion 83a toward an axis passing through the shaft hole 85.
An inclined surface 83c for facilitating the operation of setting the yoke 91 on the yoke support seat 82 is formed on the inner surface of the upper end of the projection 83b.

The bosses 88 and 8 are provided on both sides of the main plate 80.
9 are provided, and the bosses 88 and 89 are provided with screw holes 88a and 89a penetrating in the thickness direction of the base plate 80, respectively. These screw holes 88a and 89a are for screwing the cover 60 to the base plate 80, and the cover 60 has an ear piece 6 that abuts against the bosses 88 and 89.
The lugs 61 and 62 are provided with holes 61a and 62a for inserting screws B1 and B2 screwed into the screw holes 88a and 89a.

A hole 63 is provided at one end (right end in FIG. 1) of the cover 60. The hole 63 corresponds to a screw hole (not shown) provided on the lower surface of the base plate 80, and is for screwing one end of the cover 60 to the base plate 80 with a screw B3.

The motor 90 includes a rotor 93 and a rotor 93.
And a pair of coil bobbins 96 and 97 arranged opposite to each other around the rotor 93 to rotationally drive the coils 98 and 99 wound around the coil bobbins 96 and 97, respectively.
And coil bobbins 96 and 9 facing each other with the rotor 93 interposed therebetween.
7 and wound around these coil bobbins 96, 9
7 and the temporary fixing tape T
And a cylindrical yoke 91 fitted outside the coil bobbins 96 and 97 from outside. Here, the coil bobbins 96 and 97 and the coils 98 and 99 form a stator.

The main body 93a of the rotor 93 is formed of a cylindrical permanent magnet whose both ends in the diameter direction are polarized to an N pole and an S pole. The rotor shaft 92 made of resin is integrally formed such that an upper half thereof penetrates a center hole of a main body 93a formed of the cylindrical permanent magnet, and an upper end 94 slightly projects outside the main body 93a. At a position slightly before the lower end of the rotor shaft 92, an aperture blade drive lever portion 30B is integrally formed. The aperture blade drive lever 30B is provided with pins 31 and 32 that engage with the lateral grooves 41 and 51 of the aperture blades 40 and 50, respectively.
At a position separated from the rotation center on the lower surface,
The rotor 93 extends in a direction coinciding with the directions of the magnetic poles N and S of the main body 93a of the rotor 93. The lower end of the rotor shaft 92 is rotatably inserted into a shaft hole 85 provided in the bridge 100 of the main plate 80.

One of the coils 9 constituting the stator
8 are connected to terminals 98a and 98b projecting upward from the upper surface of the coil bobbin 96, and both ends of the other coil 99 are connected to terminals 99a and 99b projecting upward from the upper surface of the coil bobbin 97. Further, a magnetic piece 101 made of a soft magnetic material is attached to a concave portion 97h formed in one of the coil bobbins 97. As shown in FIG. 2A, the magnetic piece 101 is
When the diaphragm blade drive lever 30B is operated so that 50 is at an intermediate position between the maximum aperture position (the aperture stop position) and the minimum aperture position (the fully open position), the N of the rotor main body 93a is changed.
It is arranged at a position equidistant from the pole and the south pole, and has a function of generating a suction force between the north pole and the south pole, thereby applying a rotational urging force to the rotor 93. FIG. 2B shows the maximum aperture position, and FIG. 2C shows the position of the rotor 93 when the aperture blade is operated to the minimum aperture position.

As shown in FIG. 5, a concave portion 91a which engages with the projection 83b of the hook 83 of the base plate 80 is provided around the outer periphery of the yoke 91. The recess 91 a engages with the hook 83 by setting the yoke 91 on the yoke support seat 82 provided on the main plate 80. When the yoke 91 is fixed to the base plate 80 by the engagement of the concave portion 91a and the hook 83, the yoke 91
Projecting portions 96c and 97 sandwiched between the
c is provided. Further, coil bobbins 96, 97
Are provided with positioning concave portions 96e and 97e (see FIG. 4) which fit into the bobbin positioning convex portions 86 and 87 of the base plate 80, and one of the coil bobbins 96 rotatably supports the distal end portion 94 of the rotor shaft 92. Bearing part 9 with a shaft hole 95a
5 are provided. The aforementioned holding portions 96c and 97c
The yoke 91 includes a stepped portion that contacts the lower end surface. Also,
The bearing part 95 is formed of a flange-shaped part integrated with the coil bobbin 96.

Next, the operation of assembling the motor 90 will be described.

First, as shown in FIG. 3, the bearing portion 95 of the coil bobbin 96 equipped with the coil 98 is turned downward.
The rotor 93 is inserted into the rotor receiving recess 96f of the coil bobbin 96 with the tip 94 of the rotor shaft 92 facing downward.
Insert The inner dimension L2 of the rotor housing recess 96f in the axial direction.
Is formed slightly larger than the dimension L1 from the main body 93a of the rotor 93 to the tip end 94 of the rotor shaft 92. Therefore, the rotor 93 can be easily inserted into the rotor accommodating recess 96f from the lateral direction, and by moving the rotor 93 in the axial direction within the rotor accommodating recess 96f, as shown in FIG. The shaft hole 95
a. And FIG.
When the rotor 93 is mounted on one of the coil bobbins 96, the other coil bobbin 97 is abutted against the one coil bobbin 96 as shown in FIG.

The rotor housing recess 97f of the other coil bobbin 97 is provided with a projection 97g for restraining the rotor 93 from sliding. The protrusion 97g reduces the axial play t1 of the rotor 93 in the pair of coil bobbins 96 and 97 by the fitting length t between the rotor shaft 94 and the shaft hole 95a.
It is set smaller than 2 and serves to prevent the rotor shaft 94 from coming out of the shaft hole 95a. Then, after assembling the coil bobbin 97 to a state where the coil bobbin 97 is abutted on the coil bobbin 96, a temporary fixing tape T is wound around the outer periphery of the coil bobbin 96, 97 to form a rotor / stator unit.
Is externally fitted to complete the motor unit. When the yoke 91 is externally fitted to the rotor / stator unit, one end surface of the yoke 91 is brought into contact with the holding portions 96c, 96d, 97c, 97d of the coil bobbins 96, 97.

Next, an operation of assembling the assembled motor 90 to the main plate 80 will be described.

As shown in FIG. 5, the assembled motor 90 is provided with the concave portions 96e, 9e of the coil bobbins 96, 97.
7e is fitted into positioning projections 86, 87 provided inside the yoke support seat 82 of the base plate 80, and the rotor shaft 92 is
5 and press it on the yoke support seat 82. By this operation, the projection 83b of the hook 83 is engaged with the concave portion 91a of the yoke 91, and the yoke 91 is
Fixed to At the same time, the holding portions 96c, 96d, 97 of the coil bobbins 96, 97 are provided between the yoke 91 and the base plate 80.
The coil bobbins 96 and 97 are also fixed to the main plate 80 while c and 97d are sandwiched. Thus, the assembly of the motor 90 to the main plate 80 is completed.

After the motor 90 is mounted on the main plate 80, the pins 31 and 32 of the diaphragm driving lever 30B are inserted into the lateral grooves 41 and 51 of the respective diaphragm blades 40 and 50. Finally, the cover 60 is mounted on the main plate 80. The entire assembly of the electric diaphragm device according to the embodiment is completed.

In the above-described apparatus, the diaphragm blade drive lever 3
Since 0B and the rotor shaft 92 are integrated, the number of parts is reduced. In addition, the trouble of assembling the diaphragm blade drive lever 30B with high accuracy in the direction of the magnetic pole (the directions of the arrows N and S) of the main body 93a of the rotor 93 is eliminated, and the assembling work is simplified. In addition, since the bearing portion 95 for directly supporting the rotor 93 is provided on the coil bobbin 96, a dedicated bearing plate is not required, and the number of parts is reduced in that respect as well.

Also, as shown in FIG.
Since the rotor 93 is urged in the rotational direction by the magnetic piece 101 attached to the base 7, a spring having the same function can be omitted, and not only the number of parts can be reduced, but also the assembly can be simplified. Further, when the aperture blade is at the intermediate opening degree, the magnetic piece 101 is set to the N of the permanent magnet (rotor main body 93a).
Since they are arranged at the same distance from the pole and the S pole, as shown in FIG.
When the power is cut off in the state of swinging in the direction, the S pole of the rotor 93 is attracted to the magnetic piece 101, and the aperture blade is held at the full aperture (maximum aperture) position. Further, as shown in FIG. 2C, when the energization is cut off in a state where the diaphragm blade drive lever 30B swings in the direction of the arrow (b), the N of the rotor 93 is reduced.
The pole is attracted to the magnetic piece 101, and the diaphragm blade is held at the fully open (minimum diaphragm) position.

Therefore, the aperture blade can be held in any direction on the maximum aperture side or the minimum aperture side, so that power consumption at that time is not required and the life of the battery power supply can be extended. Further, at the intermediate opening, the magnetic piece 101 is located at the same distance from the N pole and the S pole, so that the urging direction of the rotor 93 changes at the intermediate opening of the aperture blade. Therefore, by controlling the energization based on the position of the intermediate opening, the aperture can be adjusted to an arbitrary opening. At this time, since the origin of the urging force is located at the position of the intermediate opening, the motor drive current required for aperture control can be reduced by half.

In the above embodiment, the hook 83 is provided on the base plate 80 and the recess 91a is provided on the yoke 91. However, the hook may be provided on the yoke 91 and the recess may be provided on the base plate 80. When the concave portion 91a of the yoke 91 is provided, its shape or the like may be freely determined by a processing method.

For example, the yoke 91 of the above embodiment is supposed to be formed by cutting a base material of a cylindrical material, and the concave portion 91a is obtained by providing a groove around the outer periphery of the cylinder. However, when the yoke 91 is formed by drawing or the like, the yoke 91 is not formed in a groove shape as in the embodiment,
If the yoke itself is formed so as to project a flange at one end of the cylinder and the concave portion is secured by the flange, troublesome processing is not required.

FIG. 6 shows an example in which a yoke is formed by drawing. Reference numeral 910 in the figure denotes a yoke formed by drawing, and reference numeral 910a denotes a flange that protrudes in a ring shape from one end of a cylindrical yoke main body. The flange 910a provides a concave portion 910b with which the projection of the hook on the main plate 80 is engaged. At the place where the projection is engaged, the operation of setting the yoke 910 on the yoke support seat 82 makes the projection simple and easy. The protrusion length of the flange 910a is set to be small so as to surely engage with the concave portion 910b.

[0044]

As described above, according to the first aspect of the present invention, as the means for urging the rotation of the rotor, the magnetic poles which generate the attracting action with the magnetic poles of the rotor are provided, so that the spring can be omitted. As a result, assembly can be simplified and production efficiency can be improved. In addition, since the position of the magnetic piece is set to an intermediate position (equidistant) between the N-pole and the S-pole of the rotor at the intermediate opening, the holding position of the aperture blade during non-operation is set at the maximum aperture position or the minimum aperture position. Can be set at an arbitrary position of the above without power supply. Therefore, it is possible to meet the two demands for the holding position of the aperture blade without consuming any battery power.

According to the second aspect of the present invention, since the diaphragm blade drive lever is formed integrally with the rotor shaft, the number of parts can be reduced. In addition, since there is no need to assemble the diaphragm blade drive lever while positioning it with respect to the rotor shaft, the assembling can be simplified. Therefore, the production efficiency can be improved.

According to the third aspect of the invention, the effects of the first and second aspects of the invention can be simultaneously obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an electric throttle device according to an embodiment of the present invention.

FIGS. 2A and 2B are diagrams schematically showing a relationship between a magnetic piece and a rotor in the same device, wherein FIG.
(B) is a diagram showing a state at the time of the maximum aperture, and (c) is a diagram showing a state at the time of the minimum aperture.

FIG. 3 is an explanatory view of a motor assembling process in the apparatus.

FIG. 4 is an explanatory diagram of a motor assembling process in the apparatus.

FIG. 5 is a longitudinal sectional view showing an assembled state of the device.

FIG. 6 is a longitudinal sectional view similar to FIG. 5, showing an assembled state of another embodiment of the present invention.

FIG. 7 is an exploded perspective view of a conventional electric diaphragm device.

[Explanation of symbols]

 30B Aperture blade drive lever 40,50 Aperture blade 80 Base plate 81 Opening 90 Motor 92 Rotor shaft 93 Rotor 93a Main body (permanent magnet) 98,99 Coil

Claims (3)

[Claims] An aperture blade for adjusting a size of an aperture for photographing light, and a motor for driving the aperture blade between a minimum aperture position and a maximum aperture position, the motor comprising a permanent magnet An electric diaphragm device comprising: a rotor engaged with the diaphragm blade; and a stator having a coil arranged on the outer periphery of the rotor and applying a current to the coil to apply a rotational force to the rotor. When the aperture blade is operated at a position intermediate between the minimum aperture position and the maximum aperture position, an attractive force is applied between the N pole or S pole at a position equidistant from the mutually adjacent N pole and S pole of the permanent magnet. An electric throttle device, wherein a magnetic piece which is generated and thereby applies a rotational urging force to a rotor is provided. 2. A base plate having an opening for photographing light, an aperture blade that is slid linearly along the surface of the base plate to adjust the size of the opening, and drives the aperture blade. An aperture diaphragm driving lever disposed between the rotor shaft of the motor and the diaphragm blade and converting the rotational movement of the rotor shaft into a linear motion of the diaphragm blade. An electric throttle device formed integrally with a rotor shaft. 3. A base plate having an opening for photographing light, an aperture blade that is slid linearly along the surface of the base plate to adjust the size of the opening, and a minimum aperture blade. A motor driven between an aperture position and a maximum aperture position,
An aperture blade drive lever arranged between the rotor axis of the motor and the aperture blade and converting the rotational motion of the rotor axis into linear motion of the aperture blade, the motor comprising a rotor having a permanent magnet and the rotor axis; An electric diaphragm device comprising: a stator having a coil disposed on the outer periphery of the rotor and applying a rotational force to the rotor by energizing the coil, wherein the diaphragm blade is positioned at an intermediate position between a minimum diaphragm position and a maximum diaphragm position. A magnetic piece that generates an attractive force between the N pole and the S pole at a position equidistant from the N pole and the S pole adjacent to each other of the permanent magnet, thereby applying a rotational urging force to the rotor. And the diaphragm blade drive lever is integrally formed with a rotor shaft.