JPH087362B2 - 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 not only for filming movies and for recording general images, but also as object recognition sensors for automatic devices such as robots and surveillance sensors for crime prevention equipment. Conventional video cameras are quite large and expensive, and although they have been widely used, they have not yet met various potential demands.

According to market research on video cameras, the potential demand is enormous, and if a low-priced microminiature video camera is developed, the huge demand can be realized by applying the camera to various fields. It is expected.

In consideration of such a current situation, at present, the development of a cylindrical ultra-compact video camera with a diameter of about 5 to 15 mm is planned, but technical development concerning such a small-diameter video camera or still camera has not been conducted in the past. I've never been told,
There are many technical problems that must be solved for the practical use of this video camera, and for example, the problem related to the diaphragm 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 impossible to use a known electromagnetically driven diaphragm device mounted on, for example, a lens shutter camera. there were. In addition, since the motor portion of the known electromagnetically driven aperture device is designed based on the lens diameter of the compact camera, it has been found that simply reducing the size of the motor portion results in insufficient output and cannot drive the aperture blades. I have.

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 that of 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 when the electromagnetically driven diaphragm device of this type is downsized, the motor output becomes so small that it becomes impossible 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 microminiature 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 are in contact with each other because they overlap each other. In the apparatus, since the length of each diaphragm blade is relatively long, the deflection angle of the diaphragm blade is small, and therefore the deflection of the diaphragm blade does not adversely affect the rotation of the diaphragm blade.

On the other hand, in the ultra-small diaphragm device as described above, since the length of each diaphragm blade is short, the deflection angle of each diaphragm blade is large, so that each diaphragm blade cannot rotate in a plane orthogonal to the optical axis. There was a risk of colliding with other diaphragm blades during rotation.

[Object of the Invention] An object of the present invention is to provide a diaphragm device suitable for a microminiature camera, and to provide a diaphragm device having a novel structure different from the conventionally known diaphragm device (or direct electric shutter). It is to be.

[Outline of the Invention] In the diaphragm device of the present invention, in order to prevent mutual interference between the diaphragm blades when the diaphragm blades rotate, a plurality of diaphragm blades that move to change the aperture amount, and a plurality of diaphragm blades. A rotating device having a plurality of engaging portions that engage with each of the plurality of diaphragm blades to move the plurality of diaphragm blades to move the blades, and the rotating member comprises a plurality of diaphragm blades. A plurality of blade supporting surfaces for supporting each of them by surface contact, each of the plurality of blade supporting surfaces being formed at different positions in the optical axis direction and having the engaging portion thereof. It is characterized by

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic vertical sectional view of a micro camera incorporating a diaphragm device according to the present invention. In FIG. 1, most of the camera structure other than the diaphragm device of the present invention is not shown. FIG. 2 is an exploded perspective view of an essential part of the diaphragm device of the present invention, FIG. 3 is a sectional view taken along the line III-III in FIG. 1, and FIG.
FIG. 1 is a perspective view showing the external appearance of a microminiature video camera incorporating a diaphragm device of the present invention.

In FIG. 1, reference numeral 1 denotes a camera body of the camera, and a diaphragm device 2 according to the present invention and a lens front lens L ₁ are built in the vicinity of the tip of the camera body 1.

A diaphragm device 2 according to the present invention comprises a main body 3 fixed to a camera body 1 and 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, permanent magnets 9 and 10 fixed to the rotor 4, and the diaphragm. The front cover 11 fixed to the main body 3 is provided with a cam groove for controlling the opening / closing operation of the blades 6-8.

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 a circumferential recess is formed on the outer peripheral surface of the front end portion of the lens holding portion 3a as a rolling path of a sphere 12 for rotatably supporting the rotor 4. 3c (see FIG. 2) is formed. Further, a screw insertion hole 3d (a stupid hole) for inserting a screw for connecting and fixing the front cover 11 is formed through 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 is inserted into an annular space formed between the lens holding portion 3a of the main body 3 and the outer cylindrical portion 3b. The inner cylindrical portion 4a is rotatably fitted to the outer peripheral surface of the lens holding portion 3a of the main body 3 via the spherical body 12. As shown in FIG. 3, a pair of cylindrically curved permanent magnets 9 and 10 are fixed at symmetrical positions with respect to the center of the rotor at two locations on the outer peripheral surface of the inner cylindrical portion 4a of the rotor 4. Further, as shown in FIG. 2, three pin holes 4c to 4e for pivotally connecting three diaphragm blades 6 to 8 are formed in the front end plate portion of the rotor 4, and each of the pin holes 4c to 4e is formed. A pivotally mounted pin 6a to 8a (6a not shown) projecting from one surface of each of the aperture blades 6 to 8 is movably inserted in 4e. As shown in FIG. 2, a notch 4f is formed in the outer cylindrical portion of the rotor 4 and the front end plate portion for positioning during the 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.

A coil unit 5 shown in FIG. 2 is disposed in an annular space formed between the lens holding portion 3a and the outer cylindrical portion 3b of the main body 3, and a plurality of coils provided in the coil unit 5 are mounted on a rotor. 4 and the permanent magnets 9 and 10
Are arranged in the annular space so as to face each other with a predetermined gap. The coil unit 5 includes an annular disc-shaped printed wiring board 13 fitted and fixed in an annular groove formed in the rear end plate portion of the main body 3, and along an arc parallel to the peripheral edge of the printed wiring board 13. It is composed of four plate-shaped coils 14 to 17 which are arranged and fixed upright on the printed wiring board so as to be curved in a cylindrical surface shape. Wiring 18 connected to each coil is attached to the printed wiring board 13, and the wiring board 18 is arranged at the position of the notch 4f of the rotor. As shown in FIG. 2, each of the coils 14 to 17 has a winding wound around an axis in the radial direction with respect to the center of the printed wiring board 13, and is an arc parallel to the peripheral edge of the printed wiring board 13. Is curved into a cylindrical surface. Of these four coils, a pair of coils 14 and 15 arranged symmetrically with respect to the axis of the printed wiring board.
Is a drive coil for generating an electromagnetic force for driving the rotor 4, and the other pair of coils 16 and 17 is a detection coil for detecting the rotation speed and the rotation direction of the rotor 4. Has become.

As shown in FIGS. 5 and 6, the printed wiring board 13 has an arc-shaped groove 13a for fitting and fixing the lower end of each coil.
And each coil is fitted into one of the grooves 13a and fixed to the printed wiring board 13. The groove 13a has a function of holding each coil in a curved shape, and a function of keeping a gap between each coil and the outer cylindrical portion of the rotor and a cap between each coil and the permanent magnet constant. Cage,
The depth t of the groove 13a is designed to be a considerably large value so that the coil does not fall or deform. The groove 13
Only the portion where the groove is arranged to make the depth of a a predetermined value or more may be thick.

Each coil has a permanent magnet 9 as shown in FIGS.
, 10 and the inner peripheral surface of the outer cylindrical portion 4b of the rotor are arranged so as to face each other with a predetermined gap, and each coil is arranged in the permanent magnets 9 and 10 as shown in FIG. It is arranged at a position closer to one side from the center in the circumferential direction.

FIG. 7 is a diagram showing the positional relationship between the permanent magnets and the coils in more detail and showing the state of the magnetic flux distribution at the rotor rest position.

As shown in FIG. 7, each permanent magnet 9 and 10 is polarized so as to become SNS from one end side to the other end side along the circumferential direction (only half of the diaphragm device is shown in FIG. 7). The center of the drive coil 14 and the center of the detection coil 16 are arranged at the boundary positions of the S pole and N pole of the permanent magnet, respectively. Therefore, as shown in FIG. 7, the driving coil 14 and the detection coil 16 have their halves in the plane orthogonal to the optical axis.
Facing the north or south pole of the other half, and the other half is a permanent magnet 9
It faces the south pole or the north pole. The coil portion that applies the drive torque to the rotor is the optical axis direction portion of the drive coil (the winding portion in the direction orthogonal to the paper surface in FIG. 7), and one of the two optical axis direction portions is a permanent magnet. N of 9
It faces the pole and the other faces the south pole.

The distribution of the magnetic flux generated from the permanent magnet 9 is as shown in the figure. When a current in the direction shown in the figure is applied to the drive coil 14 in this state, the drive coil 14 is driven by Fleming's left-hand rule.
The torques indicated by arrows T ₁ and T ₂ act on the two optical axis portions of the rotor, respectively. However, since the drive coil 14 is fixed to the main body 3, the rotor 4 moves toward the arrow A with respect to the drive coil 14. Will be moved in the direction of. When the rotor 4 is rotated in the direction of arrow A from the position shown in FIG. 7 and the two optical axis direction portions of the drive coil 14 are relatively moved to a position facing the N pole region of the permanent magnet 9, one of the drive coils The direction of the electromagnetic force acting on the lower part in the optical axis direction (the lower part in FIG. 7) is reversed, so that the rotor 4 stops.

On the other hand, when the rotor 4 is rotated in the direction of arrow A from the position shown in FIG. 7, the N pole region of the permanent magnet 9 moves away from the detection coil 16 and the S pole region (the upper S region in FIG. 7). Since the pole area) moves toward the center of the detection coil, the number of magnetic fluxes that interlink with the two winding portions of the detection coil 16 changes, so the induced current in the direction that compensates for the interlinkage magnetic flux change. Occurs in the detection coil 16, and the rotation speed (that is, the opening / closing speed of the diaphragm blades and the diaphragm change rate) and the rotation direction of the rotor 4 are detected by a control circuit (not shown) connected to the detection coil 16. .

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 in the state shown in FIG. 7, the direction of the torque acting on the rotor 4 is opposite to that in FIG. 7, and the rotor 4 is opposite to the arrow A. Driven in the direction.

FIG. 8 shows the magnetic flux distribution in the longitudinal section of the rotor 4, and the magnetic flux generated from the N pole region of the outer peripheral surface of the permanent magnet 9 is the outer cylindrical portion 4b of the rotor 4 and the front end of the rotor as shown in the figure. A magnetic circuit that returns to the S-pole region on the inner peripheral surface of the permanent magnet 9 through the plate portion is configured. The electromagnetic force generated by this magnetic circuit urges the rotor 4 downward in FIG. 8 (from the front to the rear of the expansion device), and
This has the effect of preventing the forward movement of the rotor 4 in the axial direction.

In the throttle device of this embodiment, since the rotor 4 has a double-cylindrical so-called double rotor structure, most of the magnetic flux generated from the permanent magnet passes through the rotor after passing through the rotor. Therefore, since the leakage flux is smaller than that of the known spindle motor, the leakage loss is also small, and as a result, the diaphragm device has an efficient drive source.

Further, since the electromagnetic force generated in the axial cross section serves as a force for urging the rotor 4 axially rearward, there is no risk of the rotor 4 vibrating in the axial direction, and the sphere 12 also serves as a bearing on the outer periphery of the lens holding portion 3a. There is no danger of escape from the circumferential recessed portion 3c.

A pressing ring 19 is fitted in the circumferential recess 3c so that the sphere 12 does not escape from the circumferential recess 3c.

The front cover 11 disposed in front of the aperture blades 6 to 8 is configured to be fastened to the main body 3, and a protrusion 11 b having a screw hole 11 a corresponding to a screw insertion hole 3 d of the main body 3 is formed in an axial direction. It is projected. When the diaphragm device is assembled, the protrusion 11
b 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 projection 11b are positioned.
Then, the main body 3 and the front cover 11 are fastened by screwing a screw (not shown) into the screw hole 11a through the screw insertion hole 3d.

In the front end plate portion of the front cover 11, three cam grooves 11c, 11d, for slidably inserting driven pins 6b, 7b, 8b protruding from the other surfaces of the aperture blades 6 to 8, respectively. 11e is penetrated.
In the case of the present embodiment, the cam grooves are linear grooves extending in the radial direction with respect to the axis of the front cover 11, and each cam groove 11
c to 11e are formed at positions separated from each other by 120 ° with respect to the axis.

Three diaphragm blades 6 pivotally attached to the front end plate of the rotor 4
8 rotate in parallel with the surface of the front end plate portion (within a plane perpendicular to the optical axis) around the respective pivot points in accordance with the rotation of the rotor 4. The aperture blades 6 to 8 open and close an optical path hole 3e (see FIG. 1) formed through the front end surface of the lens holding portion 3a of the main body 3. In the fully closed state where the optical path hole 3e is completely closed by the diaphragm blade, the optical axis portions of the front end portions of the diaphragm blades are overlapped and contact with each other in the optical axis direction, but the optical path hole 3e is completely opened. In the fully open state, the tips of the diaphragm blades stop at positions separated from each other. When the optical path hole 3e is fully closed, the driven pins 6b to 8b of each aperture blade are attached to the front cover.
11 moves to the outermost position of each cam groove, and when the optical path hole 3e is fully opened, the driven pins 6b, 7b, 8b of each diaphragm blade move to the innermost position of each cam groove.

When rotating the diaphragm blades 6 to 8 to close the optical path hole 3e of the lens holding portion 3a, since the diaphragm blades 6 to 8 slide on the same plane, the respective tip portions interfere with each other. become.

FIG. 9 shows a case where two blade receiving projections 4g and 4h having different heights are formed on the front end plate portion of the rotor 4 as a first embodiment of means for preventing mutual interference of the diaphragm blades. It is a thing. The blade receiving projection 4g is in sliding contact with the surface of the diaphragm blade 8, and the blade receiving projection 4h is in sliding contact with the surface of the diaphragm blade 7. The height of the projection is the height position of the moving surface of each diaphragm blade. (Axial position). Therefore, the aperture blades 8 and 7 are respectively provided with the blade receiving projections 4g and
Since it rotates while making sliding contact with 4h, the flatness of the rotating motion is guaranteed, and the diaphragm blades do not interfere with each other during the rotation.

FIG. 10 shows a second embodiment of the means in which the front end plate portion of the rotor is formed stepwise for each plane of movement of each diaphragm blade. Stepped diaphragm blade supporting surfaces 4i and 4j provided on the front end plate portion of the rotor 4 are supporting surfaces for the diaphragm blades 8 and 7, respectively, and the supporting surfaces are integrally formed with the rotor 4 (outsert molding). However, each of the supporting surfaces 4i and 4j may be formed by adhering a plastic plate on the front end plate portion of the rotor. It should be understood that each support surface is formed with pin holes 4e and 4d for inserting the pivot pins of the diaphragm blades 8 and 7.

Also in the embodiment of FIG. 10, the flatness of the movement of the diaphragm blades is guaranteed, and the diaphragm blades do not interfere with each other during the rotation.

In the above-mentioned first and second embodiments, not only the height position of the front end of each diaphragm blade in the optical axis direction is changed to prevent mutual interference, but also each diaphragm blade is not bent. Since the parallel movement ensures the flatness of the movement, it is possible to obtain the effects such as the improvement of durability and reduction of scratch noise.

Although the permanent magnet is attached to the inner cylindrical portion of the rotor 4 in the above embodiments, a structure in which the permanent magnet is attached to the inner peripheral surface of the outer cylindrical portion of the rotor may be adopted.
The rotor does not necessarily have to be a double cylinder.

EFFECTS OF THE INVENTION As described above, according to the present invention, a plurality of diaphragm blades that move to change the aperture amount and each of the plurality of diaphragm blades are moved to move the diaphragm blades. And a rotating member having a plurality of engaging portions for moving the plurality of diaphragm blades, the rotating member has a plurality of blade supporting surfaces that respectively support the plurality of diaphragm blades by surface contact. Therefore, the diaphragm blades do not locally receive high contact pressure during movement, and the operation does not become unstable.

Further, since the plurality of blade supporting surfaces are formed at different positions in the optical axis direction, the plurality of diaphragm blades do not come into contact with each other regardless of the operating state of the diaphragm blades.

Furthermore, since each of the plurality of blade supporting surfaces has the engaging portion, the rotating member and the plurality of diaphragm blades maintain the engaging relationship at different positions in the optical axis direction. Regardless of the operating state and the rotational position of the rotary member, the rotary member and each of the plurality of diaphragm blades can maintain a uniform engagement relationship.

That is, according to the present invention, it is possible to realize a diaphragm device that operates extremely stably regardless of the posture used.

[Brief description of drawings]

1 is a schematic vertical cross-sectional view of a main part of an ultra-small video camera incorporating a diaphragm device according to the present invention, and FIG. 2 is an exploded perspective view of a main part of the diaphragm device according to the present invention incorporated in the camera of FIG. 3 is a sectional view taken along the line III-III in FIG. 1, FIG. 4 is a perspective view showing the appearance of the camera shown in FIG. 1, and FIG. 5 is a coil unit which is a part of the diaphragm device. FIG. 6 is a front view of the printed wiring board of FIG. 6, FIG. 6 is a cross-sectional view of the same printed wiring board, FIG. 7 is a half-enlarged cross-sectional view of a main portion of the diaphragm device, and FIG. FIG. 9 and FIG. 10 are enlarged vertical cross-sectional views shown above, showing two embodiments of means for preventing mutual interference of diaphragm blades. 1 ...... Camera body, 2 ... Throttle device 3 ... Main body (of aperture device 2) 4 ... Rotor, 5 ... Coil unit 6-8 ... Aperture blades, 9,10 ... Permanent magnet 11 ... Previous Cover, 13 …… Printed wiring board 14,15 …… Drive coil 16,17 …… Detection coil

Claims (1)

[Claims] 1. A plurality of diaphragm blades that change an aperture amount by moving, and a plurality of diaphragm blades that move by engaging with each of the plurality of diaphragm blades in order to move the plurality of diaphragm blades. In a diaphragm device having a rotating member having a plurality of engaging portions, the rotating member has a plurality of blade supporting surfaces that respectively support a plurality of diaphragm blades by surface contact, and each of the plurality of blade supporting surfaces. Is formed so as to be at different positions in the optical axis direction, and has the engaging portions, respectively.