JPH0743491B2 - Electromagnetic drive diaphragm device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetically driven diaphragm device for mounting on an optical device such as a camera, and more particularly to an electromagnetically driven diaphragm device suitable for a micro camera.

[Background of the Invention]

Video cameras are used for shooting movies and general image recording, and are also widely used as object recognition sensors for automatic devices such as robots and surveillance sensors for crime prevention equipment. Although it is quite popular because it is quite large and quite expensive, it has not yet met various potential demands.

According to the market research on video cameras, the potential demand is enormous, and if a low-price ultra-small video camera is developed, the enormous potential demand can be revealed by applying the camera to various fields. Is expected.

Considering the current situation, the development of a cylindrical ultra-compact video camera with a diameter of 5 to 15 mm is currently being planned.
Since no technical development related to such a small-diameter video camera or a still camera has been done in the past, there are considerable technical problems that must be solved for practical use of this video camera. The problem with the device was one of them. From the viewpoint of its size, this microminiature camera is more suitable for use in an unmanned state and in remote operation while being supported by another object than in a use for supporting shooting by a person with a hand. The shutter and diaphragm device of the camera need to be of an electric type, but since the camera is very small, it is not possible to use a known electromagnetically driven diaphragm device mounted on, for example, a lens shutter camera. Met. Further, since the motor part of the known electromagnetically driven diaphragm device is designed on the basis of the lens diameter of the compact camera, it has been found that simply downsizing the motor part causes insufficient output to drive the diaphragm blades. There is.

Therefore, in order to realize the above-mentioned ultra-small camera, it was necessary to develop a new electromagnetically driven diaphragm device having a structure different from the known electromagnetically driven diaphragm device mounted on the compact camera.

Incidentally, among various electromagnetically driven diaphragm devices that have been conventionally proposed to be mounted on a compact camera or the like, a motor having an annular disc-shaped stator and an annular disc-shaped rotor is provided and There is a structure in which the diaphragm blades are pivotally attached to the rotor, but if the electromagnetically driven diaphragm device of this type is downsized, the motor output will be significantly reduced and it will not be possible to drive the diaphragm blades. If the design is made so that an output capable of driving the motor can be obtained from the motor, there is a problem that the outer diameter of the motor becomes large.

On the other hand, when designing the ultra-small diaphragm device as described above, it has been found that, in addition to the problem with the motor as described above, there are the following problems with the diaphragm blades.

Generally, in a diaphragm device, when the diaphragm is fully closed, the tips of the diaphragm blades overlap each other and are in contact with each other, so that the diaphragm blades are in a curved state in which the respective tips are pressed and bent. However, since the length of each diaphragm blade is relatively long, the deflection angle of the diaphragm blade is small, and the diaphragm blade does not adversely affect the rotation of the diaphragm blade when the diaphragm blade is narrowed.

On the other hand, in the ultra-small diaphragm device as described above, the deflection angle of each diaphragm blade is large because the length of each diaphragm blade is short,
Therefore, there is a risk that each diaphragm blade cannot rotate in a plane orthogonal to the optical axis and may collide with other diaphragm blades during rotation.

FIGS. 5 to 9 show the structure of the electromagnetically driven diaphragm device of the prior invention, which has already been filed by the present applicant, in order to clarify the difference from the invention to be described later. The structure of the electromagnetically driven diaphragm device of the prior invention will be described below.

In FIG. 5, 1 is the camera body of the camera,
The diaphragm device 2 of the prior invention and the lens front lens L ₁ are built in near the tip of the camera body 1.

As shown in FIG. 6, the diaphragm device 2 includes a camera body 1
A main body 3 fixed to the main body 3, a rotor 4 rotatable with respect to the main body 3, a coil unit 5 fixed to the main body 3,
A plurality of diaphragm blades 6 to 8 pivotally attached to the front end surface of the rotor 4.
And permanent magnets 9 and 10 fixed to the rotor 4, and a front cover 11 fixed to the main body 3 and having a cam groove for controlling the opening and closing operations of the diaphragm blades 6 to 8. .

The main body 3 has a double-cylindrical structure having a cylindrical lens holding portion 3a at its center and an outer cylindrical portion 3b concentric with the lens holding portion 3a. An annular space is formed between the inner peripheral surface of the cylindrical portion 3b and the inner peripheral surface. A lens rear lens L ₂ is housed inside the lens holding portion 3a, and the outer circumferential surface of the front end portion of the lens holding portion 3a serves as a rolling path of a sphere 12 for rotatably supporting the rotor 4 in the circumferential direction. Concave
3c (see FIG. 6) is formed. Further, a screw insertion hole 3d (dumb hole) for inserting a screw for connecting and fixing the front cover 11 is formed on the outer peripheral surface of the main body 3.

A double-cylindrical rotor 4 having an inner cylindrical portion 4a and an outer cylindrical portion 4b in an annular space formed between the lens holding portion 3a and the outer cylindrical portion 3b of the main body 3 as shown in FIG. Is inserted, and the inner cylindrical portion 4a of the rotor 4 is a lens holding portion of the main body 3.
The outer peripheral surface of 3a is rotatably fitted through the spherical body 12. As shown in FIG. 7, a pair of cylindrically curved permanent magnets 9 and 10 are fixed to the outer peripheral surface of the inner cylindrical portion 4a of the rotor 4 at symmetrical positions with respect to the center of the rotor. Further, as shown in FIG. 6, three pin holes 4c to 4e for pivotally attaching three diaphragm blades 6 to 8 are formed in the front end plate portion of the rotor 4, and each pin hole 4c to 4e for each diaphragm blade
The pivotally mounted pins 6a to 8a (6a not shown) projectingly provided on one surface of .about.8 are rotatably inserted. As shown in FIG. 6, a notch 4f is provided in the outer cylindrical portion and the front end plate portion of the rotor 4 for positioning when the throttle device is assembled.
Is formed, the screw insertion hole 3d of the main body 3 and a front cover 11 which will be described later are provided at the position of the notch when the diaphragm device is assembled.
The projecting piece of is positioned.

In the annular space formed between the lens holding portion 3a of the main body 3 and the outer cylindrical portion 3b, the coil unit 5 shown in FIG.
And a plurality of coils provided in the coil unit 5 are arranged on the outer cylindrical portion 4b of the rotor 4, the permanent magnets 9 and 10, and a pair of cylindrically curved permanent magnets 9 at symmetrical positions with respect to the center of the rotor. 10 is fixed. Further, as shown in FIG. 6, three pin holes 4c to 4e for pivotally attaching three diaphragm blades 6 to 8 are formed in the front end plate portion of the rotor 4, and each pin hole 4c to Into 4e, pivotally mounted pins 6a to 8a (6a is not shown) protrudingly provided on one surface of each of the diaphragm blades 6 to 8 are rotatably inserted. A notch 4f is formed in the outer cylindrical portion of the rotor 4 and the front end plate portion as shown in FIG. 6 for positioning during assembly of the throttle device. A screw insertion hole 3d of the main body 3 and a protrusion of a front cover 11, which will be described later, are positioned at the notch position.

In the annular space formed between the lens holding portion 3a of the main body 3 and the outer cylindrical portion 3b, the coil unit 5 shown in FIG.
A plurality of coils provided in the coil unit 5 are arranged in the annular space so as to face the outer cylindrical portion 4b of the rotor 4 and the permanent magnets 9 and 10 with predetermined gaps. ing. The coil unit 5 includes a body 3
An annular disc-shaped coil support plate 13 fitted and fixed in an annular groove formed in the rear end plate portion of the coil support plate, and the coil support plate disposed along an arc parallel to the peripheral edge of the coil support plate 13. It is composed of four plate-shaped coils 14 to 17 which are fixed upright and curved in a cylindrical surface shape. The coil support plate 13 is a printed wiring board, and a solder connection portion with the wiring 18 connected to each coil is formed on the coil standing surface of the plate 13, and the wiring 18 is a cutout of the rotor. It is located at position 4f. As shown in FIG. 6, each coil 14 to 17 has a winding wound around the radial axis with respect to the center of the coil support plate 13, and is an arc parallel to the peripheral edge of the coil support plate 13. Is curved into a cylindrical surface. Of these four coils, the pair of coils 14 and 15 arranged symmetrically with respect to the axis of the coil support plate is the rotor 4
Is a driving coil for generating an electromagnetic force for driving the rotor 4, and the other pair of coils 16 and 17 are detecting coils for detecting the rotation speed and the rotation direction of the rotor 4.

The front cover 11 arranged in front of the diaphragm blades 6 to 8 is the main body 3
And a projecting piece 11b provided with a screw hole 11a matching the screw insertion hole 3d of the main body 3 is provided in the axial direction. When assembling the expansion device, the protrusion 11b
And the screw insertion hole 3d of the main body 3 are positioned at the position of the notch 4f of the rotor 4, and the screw insertion hole 3d and the protrusion 11b are positioned.
After matching the screw holes 11a with the screw holes 11a, the main body 3 and the front cover 11 are fastened by screwing unillustrated screws into the screw holes 11a through the screw insertion holes 3d.

Three cam grooves 11c, 11d for slidably inserting driven pins 6b, 7b, 8b projecting from the other surface of each of the diaphragm blades 6 to 8 into the front end plate portion of the front cover 11. 11e is pierced.

FIG. 9 shows an electromagnetically driven diaphragm device of the second prior invention.

In FIG. 9, 110 is a front cover, 40 is a rotor, 50 is a coil unit including the coils 14 to 17 and the coil support plate 130 and a flexible printed board 180 for external drawing, and 30 is a main body which also serves as a lens barrel.

Three recesses 110a are formed on the outer peripheral surface of the front cover 110, and engagement protrusions 110b in the circumferential direction are formed inside the recesses 110a. The engagement protrusions 110b are outer cylinders of the main body 30. Department
A circumferential engaging groove 30e formed in a fitting portion 30d integrated with 30b
It is designed to fit in.

Incidentally, 110c to 110e are cam grooves into which the driven pins 6b to 8b of the diaphragm blades 6 to 8 are inserted, 110f is a jig insertion hole for positioning the front cover 110 when assembling the front cover 110 and the main body 30, Is.

The main body 30 fitted with the front cover 110 has a lens holding portion 30a.
An outer cylindrical portion 30b, a rotor support portion 30c for supporting the rotor 40, and a fitting portion 30d integral with the outer cylindrical portion 30b.
And is adapted to be fitted to the peripheral wall portion of the front cover 110 at the fitting portion 30d. A first notch 30f extending in the circumferential direction is formed at the front end edge (upper end in FIG. 9) of the fitting portion 30d, and a radial projection of the rotor 40 described later is formed in the notch 30f. The part is arranged so as to be movable in the circumferential direction. A second notch 30g that also extends in the circumferential direction is formed at the rear end edge (lower end edge in FIG. 9) of the outer cylindrical portion 30b at a position corresponding to the first notch 30f. A flexible printed board 180 is arranged in the second notch 30g. The circumferential length of the first cutout 30f corresponds to the rotation range of the rotor 40, and the edges of both ends of the cutout 30f are rotation stoppers of the rotor 40. The front end plate of the lens holder 30a has an optical path hole 3 which is opened and closed by diaphragm blades.
0i is pierced.

Like the rotor 4, the rotor 40 is a double cylinder having an inner cylindrical portion 40a and an outer cylindrical portion 40b, and a cylindrical permanent magnet 90 is fixed to the entire outer peripheral surface of the inner cylindrical portion 40a. . On the front end surface (upper end surface in FIG. 9) of the rotor 40, three diaphragm blade supporting surfaces 40c, 40d, 40e orthogonal to the optical axis are formed with steps, and the diaphragm blade 6 is formed on the surface 40c. A diaphragm blade 7 is supported on 40d, and a diaphragm blade 8 is supported on the surface 40e. A diaphragm blade 6 is provided on the surface 40c.
A pin hole 40f for inserting the pivot pin 6a of
The surface 40d has a pin hole 40g for inserting the pivot pin 7a of the diaphragm blade 7, and the surface 40e has a pivot pin 8g of the diaphragm blade 8.
Pin holes 40h for inserting 8a are formed respectively. Further, a radial protrusion 40i to be inserted into the notch 30f of the main body 30 is formed on the outer peripheral surface of the rotor 40 at a position corresponding to the diaphragm blade supporting surface 40c. The reason why the radial protrusion 40i is provided at a position corresponding to the diaphragm blade support surface 40c is to align the center of inertia of the rotor 40 with the axis of 40, and to support the mass and length of the radial protrusion 40i and the diaphragm blade support. The mass of the surfaces 40d and 40e is determined so as not to deviate the center of inertia of the rotor 40.

[Problems to be solved by the invention]

The electromagnetically driven diaphragm device of the prior invention of the above structure has the following problems.

(I) The operating angle of the rotor is determined by the cover, and the stopper position of the cover had to be changed when changing the operating angle.

(Ii) Since it is an ultra-small diaphragm device, if there is hunting with a small diaphragm, it is possible to change the stopper position of the cover so that the operation stops with the small diaphragm as a countermeasure. In the electromagnetically driven diaphragm device of the invention of the prior application, the diaphragm diameter fluctuates due to the fitting backlash of each part, and it is very difficult to obtain the target diameter.

(Iii) There has not been enough space for mounting an aperture adjusting mechanism (for example, an eccentric dowel) provided in many conventional diaphragm devices.

(Iv) If a new throttle with a different open aperture is provided, it can be achieved by changing the aperture of the member that determines the open aperture if the aperture is smaller than the existing one, but there is a dead zone that does not participate in aperture adjustment in the rotor operation. There was a drawback that it occurred and control was difficult.

[Means for Solving the Problems]

In the improved electromagnetically driven diaphragm device according to the invention,
By providing a stopper part that controls the rotation angle of the rotor separately in two members, the cover and the base, the structure allows the aperture of the diaphragm blades to be easily adjusted by changing the relative position of the cover and the base. It is a thing.

〔Example〕

An improved electromagnetically driven diaphragm device according to the present invention will be described below with reference to FIGS. In FIGS. 1 to 4, members indicated by the same reference numerals as those in FIGS. 5 to 9 are the same members as those of the diaphragm device of the prior invention, and members improved by the present invention. Is shown with the subscript 5 added to the reference numerals shown in FIGS.

1 to 4, 115 is a front cover, 40 is a rotor, and 50 is a coil unit. The coils 14 to 17, the coil support plate 130, and the flexible printed board 1 for external drawing are shown.
Including 80. Reference numeral 35 is a main body as a base that doubles as a lens barrel.

Three recesses 115a are formed on the outer peripheral surface of the front cover 115 at intervals of 120 degrees, and the engaging projections 11 in the circumferential direction are formed in the recesses 115a.
5b is formed. The engagement projection 115b is adapted to fit in a circumferential engagement groove 35e formed at a position of the fitting portion 35d integrated with the outer cylindrical portion 35b of the main body 35. Therefore, the cover 115 is rotatably supported with respect to the main body 35.

Note that 115c to 115e are cam grooves into which the driven pins 6b to 8b of the diaphragm blades 6 to 8 are inserted, 115f is a jig insertion hole for positioning the front cover 115 when the front cover 115 and the main body 35 are assembled, Is.

A notch 115h that extends in the circumferential direction is formed at the rear end edge (the lower end in FIG. 1) of the outer cylindrical portion of the front cover 115, and the notch 115h extends in the radial direction of the rotor 40 described later. The protrusion (40i) is arranged so as to be movable in the circumferential direction. The circumferential length of the notch 115h is set to a length obtained by adding an adjustment allowance to the rotation range of the rotor 40, and the edge of one end of the notch 115h is set.
115i is a rotary stopper of the rotor 40.

The main body 35 fitted with the front cover 115 includes a lens holding portion 35a, an outer cylindrical portion 35b, a rotor supporting portion 35c for supporting the rotor 40, and a fitting portion 35d integral with the outer cylindrical portion 35b. The fitting portion 35d is fitted to the peripheral wall portion of the front cover 115. A first notch 35f extending in the circumferential direction is formed at the front end edge (upper end in FIG. 1) of the fitting portion 35d, and a radial projection of the rotor 40 described later is formed in the notch 35f. The part is movable in the circumferential direction, and one end is stepped to form end edges 35h and 35i.

Further, the outer cylindrical portion 35b at a position corresponding to the first cutout 35f
A second notch 35g that also extends in the circumferential direction is formed at the rear end edge (lower end edge in FIG. 1), and a flexible printed board 180 is arranged in the second notch 35g. The circumferential length of the first notch 35f is set to a length obtained by adding the fitting portion of the front cover 115 to the rotation range of the rotor 40.
An edge 35h at one end of 5f serves as a rotation stopper for the rotor 40. The edge 35i at one end of the notch 35f is set to a length obtained by adding an adjustment allowance to the length of the fitting portion of the front cover, and the edges 35i, 35j at both ends of the notch 35f are It serves as a rotation stopper for the front cover 115. The lens holder 35a
An optical path hole 35k that is opened and closed by diaphragm blades is provided in the front end plate portion of the.

The rotor 40 has a double cylindrical shape having an inner cylindrical portion 40a and an outer cylindrical portion 40b, and a cylindrical permanent magnet 90 is fixed to the entire outer peripheral surface of the inner cylindrical portion 40a. On the front end surface (upper end surface in FIG. 1) of the rotor 40, three diaphragm blade supporting surfaces 40c, 40d, 40e orthogonal to the optical axis are formed with steps, and the surface 40c
A diaphragm blade 6 is supported on the surface 40d, a diaphragm blade 7 is supported on the surface 40d, and a diaphragm blade 8 is supported on the surface 40e. The surface 40c is provided with a pin hole 40f for inserting the pivot pin 6a of the diaphragm blade 6, and the surface 40d is provided with a pin hole 40g for inserting the pivot pin 7a of the diaphragm blade 7. The surface 40e
A pin hole 40 for inserting the pivot pin 8a of the diaphragm blade 8
Each h is drilled. Further, a radial protrusion 40i to be inserted into the notch 35f of the main body 35 is formed on the outer peripheral surface of the rotor 40 at a position corresponding to the diaphragm blade supporting surface 40c. The reason why the radial protrusion 40i is provided at a position corresponding to the diaphragm blade support surface 40c is to make the center of inertia of the rotor 40 coincide with the axial center of the rotor 40. The mass of the supporting surfaces 40d and 40e is determined so as not to deviate the center of inertia of the rotor 40.

The two step-shaped diaphragm blade supporting surfaces for supporting the diaphragm blades 7 and 8 may be formed by plastic pieces formed separately from the main body of the rotor 40.

An edge 35h as a rotary stopper provided on the main body 35 and an edge 1 as a rotary stopper provided on the front cover 115.
The rotation angle of the rotor 40 is restricted by 15i, and the diaphragm blades 6 to 8 are stopped at a diameter corresponding to the rotation angle. However, the play between the cam grooves 115c to 115e provided on the front cover 115 and the driven pins 6b to 8b of the diaphragm blades 6 to 8 and the rotor 40
There is variation in the diameter due to the looseness of the fitting between the pin holes 40f to 40h provided in the above and the pivot pins 6a to 8a of the diaphragm blades 6 to 8.

The front cover 115 and the main body 3 incorporated in the diaphragm device of this embodiment
5 is a main body 35 as shown in FIGS.
By rotating the relative position between the front cover 115 and the front cover 115, the end line 34 as a rotary stopper provided on the main body 35 is provided.
The fan angle α of h and the edge 115i of the front cover 115 serving as the rotation stopper can be adjusted to α + β or α−β, and the rotation angle of the rotor 40 is adjusted. For example, in the case of the arrangement of this embodiment, the stopper on the small aperture side is the main body 35.
It is possible to finely adjust the caliber by squeezing.

It is possible to adjust the opening diameter by disposing the rotating stopper on the front cover 115 and the opening stopper on the main body 35.

In the electromagnetically driven diaphragm device of the present embodiment having the above-mentioned structure, the drive coils 14 and 15 are supplied by supplying a current in the first direction to the respective windings of the drive coils 14 and 15 from a control circuit (not shown). The driving torque in the first direction is generated by the current in each optical axis direction portion (the winding portion in the direction orthogonal to the paper surface in FIG. 2) of the
Since it is fixed to 35, the rotor 40 is rotated counterclockwise in FIG. 2, for example. Therefore, the diaphragm blades 6 to 8 pivotally mounted on the rotor 40 swing counterclockwise around the optical axis together with the rotor 40, and swing around the respective pivoting pins 6a to 8a, so that the lens holder 35
The aperture ratio of the optical path hole 35k at the front end of a is changed to be large, for example. The driven pins 6b to 8b of the diaphragm blades 6 to 8 are provided with cam grooves 115c to 115 of the front cover 115 when the aperture ratio increases.
Sliding inward in the radial direction. In this case, each of the diaphragm blades 6 to 8 has three parallel diaphragm blade supporting surfaces 40c, 40d, 40 whose front-end surface of the rotor 40 has different positions in the optical axis direction.
Since the slide blades slide along e, the moving surfaces of the respective diaphragm blades are parallel to each other, so that the diaphragm blades do not come into sliding contact with each other, and the diaphragm blades operate lightly.

When the rotor 40 is rotated, the permanent magnet 90 is also rotated together with the rotor 40, so that the relative positions of the magnetic poles of the permanent magnet 90 and the respective optical axis parallel portions of the drive coil and the detection coil change. The number of interlinkage magnetic fluxes with respect to the optical axis direction portion of each coil also changes. Therefore, an induced current in a direction for compensating for the change in the interlinkage magnetic flux is generated in the detection coils 16 and 17, and in the control circuit connected to the coils 16 and 17, the rotation speed and rotation direction of the rotor 40 (that is, The opening / closing speed and opening / closing direction of the diaphragm blades are electrically detected.

The control circuit has a function of controlling the amount of light passing through the diaphragm device to be constant, and the actual amount of light is detected according to the aperture blade opening / closing speed detected by the detection coils 16 and 17 and the amount of light detected by another light amount detector. The light quantity is calculated, and the supply currents to the drive coils 14 and 15 are changed so that the difference between the set light quantity and the actual light quantity becomes zero.

If the direction of the current supplied to the drive coil is opposite to that described above, the direction of the torque acting on the rotor 40 is also opposite to the above, and the rotor 40 is driven in the opposite direction.

The maximum rotation angle of the rotor 40 is determined by the circumferential length of the circumferential notch 35g formed in the vicinity of the rear end portion of the outer cylindrical portion 35b of the main body 35, and the radial direction protruding from the outer peripheral surface of the rotor 40. The rotation of the rotor 40 stops at the position where the projecting portion 40i collides with both end edges of the cutout 35g.

Since the rotor 4 has a double-cylindrical so-called double rotor structure in the diaphragm device of the present embodiment, most of the magnetic flux generated from the permanent magnets is linked to the drive coil and then passes through the rotor. Therefore, since the leakage magnetic flux is smaller than that of the known spindle motor, the leakage loss is also small. As a result, the diaphragm device has an efficient drive source.

〔The invention's effect〕

As described above, by separately providing the member for controlling the rotation angle of the rotor into the cover (front cover) and the base (main body), the manufacturing cost is not increased and the diameter can be easily adjusted to a desired value. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an essential part of an improved electromagnetically driven diaphragm device according to the present invention, FIG. 2 is a cross-sectional view of the essential part in a state where various members shown in FIG. 1 are assembled, and FIG. FIG. 4A is a longitudinal sectional view of the diaphragm device of the present invention taken along the line III-III in FIG. 4, and FIGS. 4A to 4C are state diagrams of the electromagnetic drive diaphragm device of the present invention when the diaphragm aperture is adjusted. FIG. 6 is a longitudinal sectional view of an essential part of a micro camera related to the invention of the prior application by the present applicant, FIG. 6 is an exploded perspective view of the essential part of an electromagnetically driven squeezing device of the invention of the earlier application, and FIG. FIG. 8 is a longitudinal sectional view of a main part of the electromagnetic drive device of the prior application, and FIG. 9 is a cross-sectional view of the electromagnetic drive stop device of the prior application. It is a principal part perspective view. 1 …… Camera body 2 …… Throttle device 3 …… Main body (of aperture device 2) 4 …… Rotor 5 …… Coil unit 6-8 …… Aperture blade 9,10 …… Permanent magnet 11 …… Front cover 14, 15 …… Drive coil 16,17 …… Detection coil 30 …… Main body (of the diaphragm device of the prior invention) 35 …… Main body as a base (of the diaphragm device of the present invention) 40 …… Rotor 50 …… Coil unit 90 ... Permanent magnet 115 ... Front cover (of the diaphragm device of the present invention) 130 ... Coil support plate

Claims (1)

[Claims] 1. A substantially cylindrical base, a rotor rotatable with respect to the base, a cover mounted on the base, and a swingably supported by the rotor and the cover. In an electromagnetically driven diaphragm device including a plurality of diaphragm blades and an electromagnetic mechanism that applies rotational power to the rotor, a stopper portion for restricting the rotor rotation angle is provided on one side of the rotor and on the other side of the rotor. By forming the base and the cover separately from each other, and by further forming the cover so as to be rotatable by a predetermined angle with respect to the base, the aperture diameter of the diaphragm blade can be finely adjusted. An electromagnetically driven diaphragm device characterized in that