JPH0357462B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aperture device that automatically adjusts the amount of light in a cine camera, video camera, etc. according to the intensity of a light beam. Generally, this type of diaphragm device has a plurality of diaphragm blades arranged in an aperture formed around the optical axis, and these blades combine the diaphragm aperture, and the actuating member engaged with each blade is connected to a drive device. I try to adjust the amount of aperture by adjusting the amount of aperture. This drive device usually consists of a coil and a magnet that applies a magnetic field to it, and has a similar structure to a motor. Conventionally, this drive device is configured in a cylindrical shape similar to the motor, and the blades and the actuating member are assembled into a base that has an opening at the center of the optical axis separately, and the cylindrical drive device is attached to this base. It is configured as a so-called Daruma type drawing device. For this reason, when it is assembled into the lens barrel of a camera, etc., the drive unit protrudes and exhibits the external appearance shown by the dotted line in Figure 1, and a large bulge is created in the outer casing of the camera lens barrel, resulting in an undesirable external appearance. Of course, this is said to have a large impact on the user's usability. 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. 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 Fig. 2 involves arranging a plurality of coils on a circumference concentric with the optical axis as shown in the figure, and rotating a ring-shaped magnet facing the coils by controlling the energization of the plurality of coils. The movement is coupled to the actuating member of the vane. In the method shown in FIG. 3, a drive device having the same structure as that shown in FIG. 1 is formed 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 of FIGS. 2 and 3, a method is adopted in which the rotational force of the drive device is generated in the circumferential direction around the optical axis, and similarly connected to the rotatable blades. In other words, conventionally, in order to integrally configure the drive coil and magnet at the outer periphery of the optical axis opening of the substrate, both were realized based on the idea of generating the rotational force of the drive device in the direction in which the blades rotate. There were flaws that made it almost impossible. First of all, the one typically shown in Figure 2 is, for example,
No. 49-75237, JP-A-53-36227, JP-A-54-
As proposed in Publication No. 5425, the drive coil is rotated in the circumferential direction around the optical axis in the same way as the plane of movement of the blade, which is normally arranged on a plane perpendicular to the optical axis. This creates a fatal flaw in the structure of the drive coil. (The shape of the drive coil is limited to a circular shape.) If you try to make a circular motion around the optical axis with a circular coil centered on the optical axis, the shape of the drive coil is limited to a circular shape. In addition, if a compact design is desired, the outer shape of the drawing device such as the base plate is also limited to a circular shape. Therefore, if a recess is formed in the mounting space in the camera barrel due to autofocus or other mechanisms, the diameter of the camera barrel must be increased to secure a circular mounting space. (The drive coil is required to have a perfect circular shape.) In order to obtain smooth and accurate movement with a drive coil supported by a thrust bearing, the drive coil must have a perfect circular shape. It was not enough to form the material by winding it.
-As in No. 36227, secondary processing is required to create the external shape by molding etc. Therefore, the structure of the thrust bearing is complicated and expensive, and the load torque required for driving and braking the drive coil is also large. (The control torque of the drive coil is large.) If the drive coil is supported by a thrust bearing, it is difficult to drive it with a minute torque like when it is supported by a pivot bearing, and the number of windings of the momentum drive coil and the size of the magnet are increased. It becomes necessary. It is also difficult to brake the drive coil. As mentioned above, the device shown in Figure 2 is expensive and large in size, and there are inherent problems in its manufacturing technology. It's not something that can be designed. Although the drive device shown in Figure 3 has the same structure as the conventional drive device shown in Figure 1, it is difficult to manufacture it extremely small and finely. This requires extensive torque adjustment and is not cost-effective. When the present inventor integrally configures a drive coil and a magnet at the outer peripheral edge of an optical axis aperture in which a blade is incorporated, the ring-shaped drive coil is rotated in the direction of rotation of the conventional blade, that is, around the optical axis. We came to the conclusion that a method of generating rotational force by rotatably supporting it in the circumferential direction is completely unsuitable for practical use. The present invention integrates a drive coil and a magnet into the outer periphery of the optical axis aperture of a base plate incorporating blades, so that the diaphragm device can be made into the same shape as the lens barrel, rather than being limited to a circular shape. There is no bulging protrusion on the housing, the outer shape of the aperture device can be freely configured to match the camera lens barrel, the drive torque is small and the opening and closing of the aperture blades can be accurately controlled, and the device Its main purpose is to provide a diaphragm device that can be made smaller, lighter, and flatter. Therefore, the present invention provides a method for disposing a drive coil and a magnet at the outer periphery of the optical axis aperture of a frame base that incorporates blade members arranged on a plane orthogonal to the optical axis and regulating opening and closing of the optical axis aperture. A drive coil arranged in an annular manner is pivotally supported by a pair of bearing members facing each other across the optical axis aperture, and a magnet is placed in the optical axis aperture so as to cause the drive coil to swing in the same direction as the optical axis. It is placed around. As a result, the drive coil swings along a circular trajectory in the direction of the optical axis, so the coil shape is not limited to a circular shape, but can also be configured into any shape, such as an ellipse, allowing the outer shape of the device to fit into the space prepared in the lens barrel. It is possible to design it as follows. In addition, the drive coil, which swings in the same direction as the optical axis, allows the coils and magnets to be arranged side by side in the outer circumferential direction on the flat part of the frame base, making it possible to make the device flatter compared to the case where coils and magnets are stacked in layers. This design was based on the idea that the drive coil around the pivot bearing part could be accurately controlled with minute torque. Hereinafter, the configuration will be described in detail based on an illustrated embodiment. Reference numeral 1 denotes a thin plate aperture blade member, and a small hole 1a at one end will be described later. It is rotatably supported on the aperture base 3 and the optical axis O
An edge 1b forming a diaphragm aperture centered at is provided. Normally, a plurality of aperture blades 1 are set around the optical axis, but only one is shown for simplicity. 1c is a pin member 2a on the annular aperture blade operating ring 2, which is a long through hole provided in the blade plane and is arranged close to the blade plane.
engage with. The actuating ring 2 has a tongue-like piece 2b bent at its end.
A pin member 2c is provided in the radial direction. Reference numeral 2d designates projecting pieces that protrude from both sides of the pin member 2c and have bending ends in the optical axis direction. Reference numeral 3 denotes a flat cylindrical diaphragm substrate located coaxially with the optical axis, having a circular opening in the center, and a groove 3a with a concave tubular cross section on the side end surface of the actuating ring 2, and a fan-shaped groove 3a with a portion of the groove 3a cut out. A notch 3b is formed. 3c is the small hole 1 of the blade 1 planted on the outer edge of the end surface of the substrate 3.
It is a small shaft that engages with a. Reference numeral 4 denotes a cover plate which has a light flux passing hole passing through it in the center. 5 is a substantially rectangular electromagnetic device assembly base having one end in contact with the end surface of the aperture board 3, and has a light beam passage hole in the center;
Symmetrically about the axis, a convex notch 5a is provided on the outer periphery, a long hole 5b passes through the end face in the axial direction, and a fan-shaped stepped portion 5c is provided on a plane perpendicular to the axis with the long hole 5b in between. Plane portions 5d are set on both outer sides of the cutout portion, which are perpendicular to the diametric end passing through the center of the convex portion 5a and are equidistant from each other from the axis. Reference numeral 5e denotes a plate-shaped bearing member having a bearing hole in the center, which is connected to the flat surface 5d. Reference numeral 6 is a yoke member surrounded by concentric cylindrical surfaces and having a convex cross section, and its bottom portion is in close contact with the fan-shaped step portion 5c and is positioned symmetrically with respect to the axis O. Reference numeral 7 denotes a tubular arc-shaped magnet with a substantially D-shaped cross section, and the linear side of the D shape is placed in close contact with the inner wall of the yoke member 6 on the axis O side, and a magnetic field is formed between the arcuate end surface of the D shape and the outer wall of the yoke member 6. A magnetic field is formed in the radial direction of the cylindrical surface of the yoke member 6. Reference numeral 8 denotes a movable member consisting of a circular coil coaxial with the optical axis. Small shafts 8a are supported on the outside at diametrically symmetrical positions, and the coil body is brought into the magnetic field of the magnet 7. Reference numeral 9 denotes a ring-shaped plate member which is attached to the open end of the base body 5 to protect interior components. Reference numeral 9a indicates an opening for inserting a lead wire of the coil. Reference numeral 10 denotes a terminal plate, which is mounted on the plate material 9 and connects the ends of the lead wires of the coil. Reference numeral 11 is an L-shaped member having a small hole at the end of the vertical side and a small shaft 11a on the horizontal side. When the small shaft 8a of the coil is fitted into the small hole and the motion of the coil is integrally transmitted, the small shaft 11a is configured at a position where it can come into contact with the pin 2c of the actuating ring 2. In the structure of the embodiment of the present invention made up of the above-mentioned members, the actuating ring 2 is placed in the groove 3a of the aperture base 3, and the pin 2c is positioned on the side of the fan-shaped notch 3b, and the small hole 1a of the blade 1 is aligned with the small shaft 3c. Connect the hole 1c to the pin member 2a
When the cover plate 4 is covered with the open end of the base 3 by a conventional fastening means, the pin 2
To obtain a diaphragm body that can be operated by c. Therefore, the blade opens and closes when the pin 2a rotates to the right, with the direction in which the pin 2a passes through the long hole 1c from the ring side as positive, and closes when the pin 2a rotates in the opposite direction. . When the optical system is not in use, the diaphragm actuating ring 2 is biased to the closed position by the bursting member 12 so as to keep the diaphragm in the closed state to avoid unnecessary exposure of the focal plane. Further, a cover plate 9 is bonded to the open end of the base body 5 in which a coil is mounted in a magnetic gap formed between the magnet 7 and the outer side wall of the yoke member 6, thereby forming an electromagnetic device groove body. The principal axes of the diaphragm board 3 and the electromagnetic device base 5 are aligned on the optical axis O, and the notch 3b of 3 is aligned with the main axis of the electromagnetic device base 5.
The device of the present invention can be constructed on the optical axis when the opposing end surfaces of both members are bonded so as to face the elongated hole 5b of the end surface. Therefore, when a current is passed through the coil (movable member) 8 of the device of the present invention as shown in FIG. 8, the current is subjected to magnetic action within a magnetic field, and the coil receives rotational force about the support shaft 8a. Therefore, if the rotational force rotates to the right facing the head of the shaft 8a having the L-shaped member 11, the small shaft 11a of the L-shaped member 11 becomes the small shaft 2c of the actuating ring 2.
The ring 2 is rotated clockwise around the optical axis, and the small shaft 2a on the operating ring 2 is rotated clockwise while engaging with the elongated hole 1c of the aperture blade 1, and the aperture blade 1 is rotated in the aperture opening direction. By rotating the aperture, an appropriate diaphragm aperture can be synthesized depending on the magnitude of the input current value. Note that the small shaft 11a of the L-shaped member 11 and the operating ring 2
The small shaft 2c is always kept in contact with the small shaft 2c by the spring 5f. Further, the structure of the claims of the present invention and the structure of the illustrated embodiment are compared as follows.

【table】

[Table] As can be understood from the above description, the present invention has a drive coil arranged around an optical axis aperture on a frame base to which a blade member forming an aperture aperture is attached, and facing each other across the optical axis aperture. It is supported by a pair of bearing members so that it can swing freely in the same direction as the optical axis, and a magnet that causes the coil to swing in the same direction as the optical axis is also placed on the outer periphery of the optical axis opening of the frame base. It has the following characteristics. (1) A drive coil and a magnet are disposed on the outer periphery of the optical axis opening of the frame base to which the blade member is attached, and the drive coil is disposed through a bearing member, and the magnet is disposed directly on the outer periphery of the optical axis opening of the frame base to which the blade member is attached. It is possible to reduce the size of the camera lens barrel. (2) The drive coil is a pair of bearing members that sandwich the optical axis aperture, and swings in the direction of the optical axis (in a posture parallel to the blades perpendicular to the optical axis), so the shape of the drive coil is not limited to circular, but can also be elliptical or polygonal. You can freely design the shape etc. Therefore, the external shape of the device, which depends on the shape of the drive coil, can be selected with some degree of freedom, and the diaphragm device can be configured according to the space provided in the lens barrel of the camera. (3) The drive coil is supported by a pair of bearing members in a position parallel to the blades, and swings about the support shaft in the same direction as the optical axis. Therefore, the coil and magnet can be arranged side by side around the optical axis aperture, making it possible to make the device flatter and smaller. Furthermore, the supporting structure of the drive coil is simple, and even with a small generated torque, the swing motion can be performed without loss, and the braking is easy.

[Brief explanation of drawings]

FIGS. 1, 2A, 2B, and 3 are explanatory views of conventional devices, and FIGS. 4 to 7 show an embodiment of the present invention. FIG. 4 is a perspective view showing the main parts of the present invention, FIGS. 5 and 6 are perspective views showing the arrangement of members in the present invention, and FIG. 7 is a perspective view of the overall configuration of the present invention (however, electromagnetic The device assembly base 5 shows perspective views from the front and back, and is a part of the device.), No. 8
The figure is a perspective view of a main part of the present invention in an operating state. 1...Aperture blade, 2...Aperture blade operating member, 7
... Magnet member, 8 ... Coil, 11 ... L-shaped member.

Claims (1)

[Claims] 1. A fixed magnet and a movable drive coil facing the fixed magnet cause the drive coil to move, and the movement of the drive coil is transmitted to a blade member forming an aperture aperture to adjust the amount of light. In the aperture device, a frame base having an optical axis aperture in the center is provided with (a) a blade member for regulating the opening and closing of the optical axis aperture, (b) a blade actuating member that engages with the blade member and adjusts the aperture aperture, and ( c) a pair of bearing members facing each other across the optical axis aperture, and (d) an annular ring disposed around the optical axis opening and supported so as to be swingable in the same direction with respect to the optical axis by the pair of bearing members. a drive coil; (e) a magnet disposed around the optical axis aperture and having a magnetic field that causes the drive coil to swing in the same direction as the optical axis; A diaphragm device comprising a motion transmitting member and a motion transmitting member that transmits the motion to the operating member. 2. The drive coil is constructed by winding a coil material into an annular shape, and the drive coil is swingably attached to the bearing member so as to have a motion component in the same direction and a motion component in a direction orthogonal to the optical axis. and the magnet is arranged around the optical axis aperture so as to cause the drive coil to move in the same direction as the optical axis, and the drive coil moves along the optical axis via a motion transmission member connected to the magnet. 2. The aperture device according to claim 1, wherein a motion component in a direction orthogonal to the blade actuating member is transmitted to the blade actuating member. 3. A frame base having an optical axis aperture in the center, a blade member whose base end is supported on the frame base to regulate opening and closing of the optical axis aperture, and a blade operating member that engages with the blade member and adjusts the diaphragm aperture. A pair of bearing members facing each other through the optical axis aperture provided on the frame base, and an annular drive coil supported so as to be swingable in the same direction as the optical axis by the bearing members and disposed around the optical axis aperture. a magnet provided on the inner peripheral side of the drive coil along the optical axis opening of the frame base and having a magnetic field that causes the drive coil to swing in the same direction as the optical axis; A diaphragm device comprising: a yoke disposed on the outer peripheral side of the drive coil of the frame base; and a motion transmission member that transmits the swing motion of the drive coil to the blade actuating member.