JPS6321173B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aperture device that adjusts the amount of light in a cine camera, video camera, etc.

[Conventional technology]

Generally, this type of aperture device has a plurality of aperture blades arranged around the periphery of an optical axis aperture formed around the optical axis.
These blades combine the aperture aperture, and the actuating member engaged with each blade is connected to a drive device to adjust the amount of aperture.

This drive device usually consists of a coil and a magnet that applies a magnetic field to the coil, and has a similar structure to a motor.

Conventionally, this drive device was configured in a cylindrical shape similar to the motor, and the blades and the actuating member were assembled into a base with an optical axis aperture formed separately, and the cylindrical drive device was attached to this base, resulting in a so-called Daruma type. It is configured as a diaphragm device.

For this reason, when it is assembled into the lens barrel of a camera, etc., the driving device part protrudes and takes on the appearance shown by the dotted line in Figure 1, and a large bulge is created in the outer casing of the camera lens barrel, which is a problem in terms of external design. Of course, it is said that this greatly affects the usability of the user.

Conventionally, for example, video cameras and the like have always had to be made smaller, but in order to make the lens barrel smaller and easier to use, it has become necessary to make the aperture device, which determines the shape of the outer housing, close to the same diameter as the lens system. has been done.

[Problem that the invention seeks to solve]

Therefore, it became necessary to improve the drive device exhibiting the Daruma type, and attempts were made to integrate the drive device with the base to which the blades were attached, and the method shown in FIG. 2 or 3 was proposed.

The method shown in Figure 2 involves arranging a plurality of coils on a circumference concentric with the optical axis as shown in Figure 2B, and rotating a ring-shaped magnet facing the coils by controlling the energization of the plurality of coils. The rotation of the blade is connected to the actuating member of the blade.

In the method shown in FIG. 3, a drive device having the same structure as that shown in FIG. 1 is constructed in an extremely small size, and a plurality of drive devices are arranged in parallel on a circumference concentric with the optical axis.

Therefore, in both FIGS. 2 and 3, the rotational force of the drive device is generated in the circumferential direction around the optical axis,
Similarly, a method is used in which it is connected to a blade that rotates in this direction.

In other words, all of them had the drawback that they were almost impossible to implement, based on the idea that the rotational force of the drive device was generated directly in the direction in which the blades rotated.

In other words, in the case of the one in Figure 2, it is not only extremely difficult to manufacture the ring-shaped magnet, but also requires a special bearing method to support it so that it can rotate. Moreover, it is clear that it is not suitable for practical use because it rotates even if the generated torque is made very small due to miniaturization.

Although the drive device shown in Figure 3 has the same structure as the conventional one, it is difficult to manufacture it extremely small and finely.
Moreover, multiple units must be arranged side by side, and delicate torque adjustment is required when rotating the blades using the combined torque, which is not suitable in terms of cost.

As a result of various attempts to miniaturize the diaphragm blades and the drive device, this invention was developed by the conventional method of generating the rotational force of the drive device in the rotational direction of the blades, that is, in the circumferential direction around the optical axis. It was concluded that it was not suitable for practical use.

[Purpose of the invention]

This invention enables further flattening, improves magnetic shielding from external magnetic fields and the outside world, and evens out the magnetic flux density of the magnet acting on the drive coil, reducing the drive torque generated in the drive coil. The object of the present invention is to obtain an aperture device that can perform stable and smooth aperture control.

[Means for solving problems]

In order to achieve the above object, the present invention provides a concave member having an inner wall and an outer wall that face each other along the periphery of an optical axis opening provided in a base, and a connecting portion that connects these inner and outer walls. A magnet, which is provided around the periphery of the opening and forms a magnetic field in a direction perpendicular to the optical axis, is fixed to the inner wall surface of the recessed member parallel to the optical axis, and an oscillating member that is provided in the magnetic field formed by the magnet and which forms a magnetic field in a direction perpendicular to the optical axis. A movable drive coil is supported by a pair of shaft bearings located on both sides of the optical axis opening, and is interposed between the magnet and an inner wall surface of the concave member facing the magnet, and the drive coil The swinging motion of the blade is transmitted to the blade operating member by a motion transmission member, and the blade operating member is rotated.

[Embodiments of the invention]

Hereinafter, an embodiment of the present invention will be explained with reference to FIGS.
This will be explained with reference to FIG.

The aperture device of this embodiment has thin plate-like aperture blades 1
, a blade operating member disposed close to the blade plane, for example, an annular aperture blade actuating ring 2, a flat cylindrical aperture base 3, a cover plate 4, and a generally short cylindrical blade whose one end is in contact with the end surface of the aperture base 3. A base body 5 with an electromagnetic device, a pair of yoke members 6 having a concave cross section, an annular arc-shaped magnet 7 having a substantially D-shaped cross section, a circular drive coil 8 coaxial with the optical axis, and an annular plate member. 9, a terminal plate 10, and a motion transmitting member such as an L-shaped member 11.

The aperture blade 1 has a small hole 1a rotatably supported on the aperture base 3, an edge 1b forming an aperture opening centered on the optical axis O, and a through hole 1c provided in the flat surface of the blade. have. Although a plurality of aperture blades 1 are normally provided around the optical axis, only one aperture blade 1 is shown and the other aperture blades 1 are omitted.

The actuation ring 2 includes a pin member 2a that engages with the long through hole 1c of the blade 1, and a tongue-like piece 2 bent at the end.
b, a pin member 2c provided on the tongue-like piece 2b to protrude outward, and protruding pieces 2d protruding from both sides of the pin member 2c and bent in the optical axis direction.

The blades 1 are opened and closed by the engagement between the pin 2a and the elongated hole 1c, so that the blades 1 open when the actuation ring 2 is rotated counterclockwise, and closed when the actuation ring 2 is rotated in the opposite direction.

In order to avoid unnecessary exposure of the focal plane when the optical system is not in use, the operating ring 2 is normally urged in the closing direction by the elastic member 12 so as to keep the diaphragm in the closed state.

The diaphragm base 3 has a central circular aperture 3d (optical axis aperture) located coaxially with the optical axis O, a groove 3a with a concave cross-section and an annular groove provided on the side end surface of the actuating ring 2, and a groove 3a that is aligned with the circular aperture 3d (optical axis aperture) located coaxially with the optical axis O. A fan-shaped notch 3b that has been partially removed and a small hole 1a of the blade member 1 planted on the outer edge of the end surface of the base 3
It has a shaft 3c that engages with the shaft 3c.

That is, the operating ring 2 is inserted into the groove 3a of the aperture base 3, the pin 2c is positioned on the fan-shaped notch 3b side,
The small hole 1a of the blade 1 is engaged with the shaft 3c, and the long hole 1c is engaged with the pin member 2a.

The cover plate 4 has a light flux passing hole 4a in the center, and the base plate 3
attached to the open end of the

The electromagnetic device assembly base 5 has a light flux passage hole 5f in the center, a convex cutout 5a projecting to the outer circumference symmetrically with respect to the optical axis O, and a long hole 5b penetrating in the optical axis direction.
, a planar fan-shaped step 5c provided perpendicularly to the optical axis O across the elongated hole 5b, and a plan view 5d provided equidistantly from the optical axis O on the outside of the convex notch 5a. , and a plate-shaped bearing member 5e that is attached to the flat portion 5d and has a bearing hole 5g in the center.

Then, the aperture base 3 and the electromagnetic device assembly base 5 are connected with the notch 3b facing the elongated hole 5b.

As shown in FIGS. 7 and 8, the yoke member 6 has an arcuate inner wall 6a, an outer wall 6b facing the inner wall 6a, and a connecting portion 6c that connects the inner wall 6a and the outer wall 6b. The portion 6c is in close contact with the fan-shaped step portion 5c, and is provided symmetrically with respect to the optical axis O at the periphery of the light flux passage hole 5f.

The magnet 7 is fixed to an inner wall surface parallel to the optical axis O of the yoke member 6, for example, the inner wall 6a.

The drive coil 8 has a pair of shafts 8a and lead wires 8b outside the diametrically symmetrical positions, and these shafts 8a
is supported by the bearing hole 5g of the bearing member 5e, and the magnet 7
and the outer wall 6b of the yoke member 6.

The plate material 9 is attached to the open end of the base body 5 to protect the interior components, and has an opening 9a for passing the lead wire of the drive coil 8.

A lead wire 8b of the drive coil 8 mounted on the plate member 9 is connected to the terminal plate 10.

The L-shaped member 11 has a shaft 8 provided at the vertical side end.
The shaft 11a has a small hole 11b fitted into the shaft 11a, and a shaft 11a positioned so as to be able to come into contact with the pin 2c of the actuating ring 2.

In such a configuration, when a current is passed through the drive coil 8, the drive coil 8 receives rotational force about the support shaft 8a. In Fig. 4, the drive coil 8 is connected to the shaft 8.
By rotating clockwise around a, the small shaft 1 of the L-shaped member 11
1a presses the shaft 2c of the actuating ring 2, rotates the aperture blades 1 in the opening direction, and synthesizes an appropriate aperture aperture depending on the magnitude of the input current value.

According to the embodiment described above, the magnet 7 that forms the magnetic field φ in the direction orthogonal to the optical axis O is fixed to the inner wall surface of the yoke member 6 that is parallel to the optical axis O, and the magnetic field φ that the magnet 7 forms A drive coil 8 which can swing freely across the inside in the optical axis direction is connected to a pair of bearing parts (bearing hole 5g of bearing member 5e) located across the light flux passage hole 5f.
and shaft 8a), is interposed between the magnet 7 and the inner wall surface of the yoke member 6 facing the magnet 7, and transmits the swinging motion of the drive coil 8 to the actuating ring 2 by an L-shaped member 11. Since the actuation ring 2 is rotatable, the magnet 7 and the drive coil 8 can be arranged side by side with respect to the optical axis O, and the magnet 7 and the drive coil 8 can be stacked up and down in the optical axis direction. It can be made more flat than the conventional one.

The yoke member 6 is composed of an inner wall 6a facing along the periphery of the circular opening 3d provided in the base 3, an outer wall 6b, and a connecting portion 6c connecting the inner wall 6a and the outer wall 6b. Since it is provided at the periphery of the light flux passing hole 5f of the attachment base 5 (that is, the periphery of the circular opening 3d), the magnetic field φ loops through a path with as low magnetic resistance as possible as shown in FIG. is completed, and moreover, the magnetic field φ generated by the magnet 7 becomes approximately the same magnetic field φ, the magnetic flux density from the magnet 7 acting on the drive coil 8 is made uniform, and the drive torque generated in the drive coil 8 becomes equal to that of the drive coil 8. It becomes constant regardless of the deflection angle, the driving torque is stable, and smooth aperture control can be performed.

〔Effect of the invention〕

In summary, the present invention provides a concave member at the periphery of the optical axis opening provided on the base, which includes an inner wall and an outer wall that face each other along the periphery of the optical axis opening, and a connecting portion that connects these inner and outer walls. A magnet that forms a magnetic field in a direction perpendicular to the optical axis is fixed to an inner wall surface of the concave member that is parallel to the optical axis, and a drive coil that can swing freely across the magnetic field formed by the magnet in the optical axis direction is provided. , supported by a pair of shaft bearings located on both sides of the optical axis opening, and interposed between the inner wall surface of the recessed member facing the magnet and the magnet;
Furthermore, the swinging motion of the drive coil is transmitted to the blade actuating member by the motion transmission member, and the blade actuating member is rotated, so that further flattening is possible and the resistance to external magnetic fields and the outside is increased. It is possible to obtain an aperture device with improved magnetic shielding properties, uniform magnetic flux density of the magnet acting on the drive coil, stable drive torque generated in the drive coil, and smooth aperture control.

[Brief explanation of the drawing]

FIGS. 1, 2A and 2B, and 3 are explanatory diagrams of conventional devices, respectively. FIGS. 4 to 8 are diagrams showing one embodiment of the present invention. Figure 4 is a perspective view showing the main parts, Figures 5 and 6 are perspective views showing the arrangement of each member, and Figure 7 is a perspective view showing the overall configuration (however, the electromagnetic device assembly base 5 is shown from the front and back. FIG. 8 is a sectional view of the yoke member and the magnet for explaining the effect. 1...Aperture blade, 2...Aperture blade operating ring,
3... Aperture base, 4... Cover plate, 5... Electromagnetic device assembly base, 6... Yoke member, 7... Magnet, 8...
Drive coil, 9...Plate material, 10...Terminal board, 11
...L-shaped member.

Claims (1)

[Scope of Claims] 1. A base having an optical axis aperture, a blade whose base end is supported on the base to form an aperture aperture, and a blade that rotates along the optical axis aperture to open and close the blade to open and close the aperture. A diaphragm device equipped with a blade actuating member that adjusts the size of the aperture, (A) comprising an inner wall and an outer wall that face each other along the periphery of the optical axis aperture, and a connecting portion that connects these inner and outer walls; a recessed member provided at the periphery of the optical axis opening; (B) a magnet fixed to an inner wall surface of the recessed member parallel to the optical axis and forming a magnetic field in a direction perpendicular to the optical axis; and (C) this magnet. is interposed between the inner wall surface of the concave member facing the magnet and is supported by a pair of shaft bearings located across the optical axis opening, and the magnetic field formed by the magnet is moved in the optical axis direction. A diaphragm device comprising: a drive coil that can swing freely across; and (D) a motion transmission member that transmits the swing motion of the drive coil to the blade actuation member and rotates the blade actuation member. .