JP2016012029A - Diaphragm device, and camera provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm device that can improve accuracy of a diaphragm opening by eliminating backlash occurring between a connecting shaft of a diaphragm blade and a cam groove of a driving ring.SOLUTION: A driving ring 4 is rotatably disposed in a recess of a bottom plate 1, and has seven cam grooves 4a. A diaphragm blade 3 has a rotating shaft 3a rotatably attached to the bottom plate 1, and a connecting shaft 3b inserted into the cam groove 4a of the driving ring 4. Cam surfaces 4a-1, 4a-2 are provided in the cam groove 4a, which are in contact to each other with no gap at all times while sandwiching the connecting shaft 3b, thereby improving accuracy of a diaphragm opening.

Description

  The present invention relates to a diaphragm device in which a plurality of diaphragm blades are reciprocally rotated in the same direction at the same time by a rotating ring to change the aperture size of the diaphragm formed in cooperation, and a camera equipped with the diaphragm device About.

  Conventionally, as a technology in such a field, for example, there is the following Patent Document 1. In the diaphragm device described in Patent Document 1, the output gear of the stepping motor 2 is transmitted from the output gear 4 provided on the output shaft 3 to the wind turbine 5 through the idler gear 8 urged in one direction by the leaf spring 10. Then, a plurality of aperture blades 6 interlocked with the wind turbine 5 are relatively moved to set an arbitrary aperture opening diameter. This eliminates mechanical backlash (so-called backlash) due to the meshing of the gears between the gears, and achieves high precision of the aperture diameter.

JP 2003-121901 A

  However, the throttle device described in Patent Document 1 can eliminate play from the output gear to the wind turbine if the throttle wind turbine comes into contact with the stop at the maximum throttle aperture position or the minimum throttle aperture position depending on the assembly accuracy. However, there is a possibility that the backlash between the windmill groove and the blade cam follower pin of the diaphragm blade cannot be eliminated.

This invention makes it an example of a subject to cope with the said situation. That is, an object of the present invention is to provide a diaphragm device capable of improving the precision of the diaphragm aperture by eliminating the backlash between the diaphragm blade and the rotating ring (drive ring) that directly affects the precision of the diaphragm aperture, and a camera having the same. To do.

  In order to achieve the above object, the diaphragm device according to the present invention includes a base plate having a circular opening, and each of which has a connecting shaft and is rotatable to the base plate at substantially equal angular intervals in the circumferential direction. And a plurality of diaphragm blades that cooperate to form an aperture opening, and can be rotated around the aperture and formed at substantially equiangular intervals in the circumferential direction, and the coupling shafts are individually fitted. A drive ring having a plurality of cam grooves, and the connecting shaft is always in contact with two cam surfaces formed to be parallel to the inside of the cam grooves. It is characterized by.

  In the present invention, it is preferable that the cam surfaces of the cam grooves are formed on different surfaces of the drive ring.

  In the present invention, it is preferable that the cam surface interval of the cam groove is equal to or smaller than the diameter of the connecting shaft.

  Furthermore, the camera of the present invention is characterized by including the above-described diaphragm device of the present invention.

  According to the diaphragm device having the above-described configuration, the cam groove of the drive ring that fits with the coupling shaft of the diaphragm blade is provided with a cam surface that is always in contact with the coupling shaft, so that the play between the diaphragm blade and the driving ring is reliably ensured. Can be eliminated. Thereby, the precision of the aperture opening can be improved with a simple configuration.

The top view of the Example which showed the control state of the largest aperture opening seen from the cover board side. FIG. 2 is a main part sectional view of FIG. 1. The top view of the drive ring used for the Example seen from the main plate side. The top view of the Example which showed the state in the middle of narrowing down looked like FIG. The top view of the Example which showed the control state of the minimum aperture stop looked like FIG.

  Embodiments of the present invention will be described with reference to the illustrated examples. The diaphragm device of the present invention can be configured as a single diaphragm device or as a diaphragm device unitized with the shutter device, but the embodiment is configured as a single diaphragm device.

  First, the configuration of this embodiment will be described with reference to FIGS. In the diaphragm device of this embodiment, a blade chamber is formed between the base plate 1 made of synthetic resin and the cover plate 2. The cover plate 2 is attached to the base plate 1 by appropriate means, and has substantially the same outer shape as the base plate 1, but in FIG. 1, a part of the cover plate 2 is shown for easy understanding of the configuration of the blade chamber. Only is shown and is omitted in FIGS. The base plate 1 of the present embodiment has a circular opening 1a centered on the optical axis O at the center thereof. The cover plate 2 also has a circular opening 2a centered on the optical axis at the center. In the present embodiment, the opening 1a of the base plate 1 regulates the exposure opening (maximum aperture diameter).

  On the surface of the base plate 1 on the blade chamber side, a recess 1b is formed so as to surround the opening 1a. Seven blade mounting holes 1c are formed on the bottom surface of the recess 1b, that is, the surface on the blade chamber side of the base plate 1 at substantially equiangular intervals around the optical axis o. In FIG. 5, only one of them is labeled. Further, the base plate 1 is formed with a total of eight guide portions 1e having similar shapes to each other at the outer peripheral edge of the recess 1b. In FIGS. 1, 4 and 5, one of them is shown. Only the sign is attached. Further, the base plate 1 is formed with stopper portions 1e and 1f for restricting rotation of a drive ring 4 described later.

  In the concave portion 1b, seven diaphragm blades 3 formed by synthetic molding of synthetic resin are arranged. Since all of them have the same shape, FIG. 1, FIG. 4, FIG. In FIG. 1, only one of them is labeled. The diaphragm blade 3 has a rotating shaft 3a on the base plate 1 side and a connecting shaft 3b on the cover plate 6 side. The rotating shaft 3a is rotatably attached to the blade mounting hole 1c. Yes.

  In the recess 1b, a drive ring 4 is disposed on the cover plate 2 side of the diaphragm blade 3, the outer peripheral surface is in contact with the eight guide portions 1e, and the optical axis is the center. It can be reciprocated. The drive ring 4 has seven cam grooves 4a each having a long hole shape at substantially equal angular intervals around the optical axis o, and two cam surfaces 4a-1 formed in the respective cam grooves 4a. 4a-2, the connecting shafts 3b are individually inserted. In FIGS. 1, 4 and 5, the cam grooves 4a and the cam surfaces 4a-1 and 4a-2 are one by one. The sign is attached only. Further, the drive ring 4 is provided with a tooth portion 4b and an overhang portion 4c on a part of the outer peripheral portion.

  The two cam surfaces 4a-1 and 4a-2 formed in the long hole-shaped cam groove 4a are each formed in a convex shape parallel to the inside from both sides of the cam groove 4a, and the optical axis. It is formed on a different surface side of the drive ring 4 in the direction o. Further, the two cam surfaces 4 a-1 and 4 a-2 are formed so as to be thinner than the thickness of the drive ring 4 in the direction of the optical axis o. And there is no gap between the two cam surfaces 4a-1 and 4a-2 and the substantially cylindrical connecting shaft 3b. That is, the diameter of the connecting shaft 3b and the distance between the two cam surfaces 4a-1 and 4a-2 are the same, or the distance between the two cam surfaces 4a-1 and 4a-2 is smaller than the diameter of the connecting shaft 3b. It has become. Therefore, when the distance between the two cam surfaces is smaller than the diameter of the connecting shaft 3b, the connecting shaft 3 is slightly deformed so that it always comes into contact with the cam surface.

  In the present embodiment, such a drive ring 4 is reciprocally rotated by a step motor within a predetermined rotation angle range. Although this step motor is attached to the main plate 1 outside the blade chamber, since its configuration is well known, the detailed configuration thereof is not shown in FIGS. 1, 4, and 5. Only the rotor 5 made of permanent magnets arranged outside the room and the output gear 5a attached to the output shaft penetrating the blade chamber side are shown. Further, the main plate 1 is attached to a parent-child gear (two-stage gear) 6 so as to be rotatable.

  Next, the operation of this embodiment will be described. FIG. 1 shows a state in which the seven aperture blades 3 fully open the opening 1 a, that is, a control state of the maximum aperture opening. The connecting shaft 3 b of each aperture blade 3 has two cam grooves 3. The two cam surfaces 4a-1, 4a-2 are in contact with no gap. When the subject light is darker than the predetermined brightness, the image is taken as it is, but when the subject light is brighter than the predetermined brightness, the rotor 5 of the step motor is rotated clockwise. As a result, the drive ring 4 is rotated clockwise via the output gear 5a and the parent / gear gear 6, so that the seven diaphragm blades 3 connect the connecting shaft 3b to the cam surfaces 4a-1, 4a- of the cam groove 4. 2 and simultaneously rotated counterclockwise around the rotation shaft 3a to enter the opening 1a, and the aperture of the aperture is reduced by the cooperation of the aperture blades 3.

  Then, when the predetermined aperture opening is obtained, the rotor 5 stops and photographing is performed. FIG. 4 shows a state in which the seven diaphragm blades 3 have reached the diaphragm aperture control position halfway between the maximum diaphragm aperture and the minimum diaphragm aperture. 4, since the connecting shaft 3 b of the diaphragm blade 3 is in contact with the cam surfaces 4 a-1 and 4 a-2 of the cam groove 4 without a gap, the cam surface and the connecting shaft The play between the two can be eliminated. Further, as shown in FIG. 2, the cam surfaces 4 a-1 and 4 a-2 are arranged during the period from the control state of the maximum aperture opening shown in FIG. 1 to the halfway aperture opening control position shown in FIG. 4. Since it is formed thinner than the thickness of the drive ring, the influence of the friction generated with the connecting shaft 3b can be reduced, so that the diaphragm blade can be smoothly rotated.

  Further, in FIG. 5, the drive ring 4 is further rotated clockwise than in the state of FIG. 4, the overhanging portion 4 c is stopped by contacting the stopper portion 1 f, and the seven diaphragm blades 3 are Although the state in which the control position of the minimum aperture opening is shown is shown, the connecting shaft 3b of the aperture blade 3 is in contact with the cam surfaces 4a-1 and 4a-2 without any gaps until reaching this state. Therefore, the play between the cam surface and the connecting shaft can be eliminated. Furthermore, since the friction between the cam surface and the connecting shaft can be reduced, the aperture blade 3 can be smoothly rotated.

  In this way, when shooting is completed, the rotor 5 is rotated counterclockwise, the drive ring 4 is rotated counterclockwise, and the seven diaphragm blades 3 are rotated clockwise. And those rotations are stopped when the overhang | projection part 4c of the drive ring 4 contact | abuts to the stopper part 1e. This state is the state shown in FIG. Although the present embodiment has been described on the assumption that FIG. 1 is a state before the start of photographing, it is needless to say that the state shown in FIG. 5 may be changed to a state before the start of photographing.

  Thus, in this embodiment, the cam ring 4a-1, 4a-2 of the cam groove 4a and the connecting shaft 3b are in contact with each other without any gap, regardless of the rotational position of the drive ring 4. The backlash between the surfaces 4a-1, 4a-2 and the connecting shaft 3b can be eliminated. Furthermore, since the cam surfaces 4a-1 and 4a-2 are thinner than the thickness of the drive ring 4 in this embodiment, even if the cam surfaces 4a-1 and 4a-2 and the connecting shaft 3b are always in contact with no gap, Since the friction between the cam surfaces 4a-1 and 4a-2 and the connecting shaft 3b can be reduced, the operation of the aperture blade 3 is stabilized, and a predetermined aperture opening can be obtained more appropriately.

  In this embodiment, as shown in FIG. 2, the two cam surfaces are formed on different surfaces of the drive ring in the optical axis direction, but the two cam surfaces are the same. It may be formed on the surface side. In the present embodiment, the rotation shaft of the diaphragm blade is formed on the diaphragm blade itself. However, it is possible that the shaft is erected on the base plate and the hole formed on the diaphragm blade is rotatably attached to the shaft. . Furthermore, in this embodiment, the diaphragm blades are formed by integral molding of synthetic resin. However, if at least the connecting shaft is made of synthetic resin, the other parts are limited to synthetic resin. It is not something.

  As described above, the aperture device of the present invention can achieve improvement in aperture aperture accuracy, and thus can be applied to optical devices such as single-lens cameras and mirrorless cameras.

DESCRIPTION OF SYMBOLS 1 Ground plate 1a Opening part 1c Blade attachment hole 1e, 1f Stopper part 2 Cover plate 3 Diaphragm blade 3a Rotating shaft 3b Connection shaft 4 Drive ring 4a Cam groove 4a-1, 4a-2 Cam surface 5 Rotor O Optical axis

Claims (4)

A plurality of ground plates each having a circular opening and each having a connecting shaft and rotatably mounted on the ground plate at substantially equal angular intervals in the circumferential direction to form a diaphragm opening. A drive having a plurality of diaphragm blades and a plurality of cam grooves that are rotatable around the opening and formed at substantially equal angular intervals in the circumferential direction and into which the connecting shafts are individually fitted. And a ring, and the connecting shaft is always in contact with two cam surfaces formed to be parallel to the inside of the cam groove. 2. The aperture device according to claim 1, wherein cam surfaces of the cam grooves are respectively formed on different surfaces of the drive ring. The aperture device according to claim 2, wherein an interval between cam surfaces of the cam grooves is equal to or smaller than a diameter of the connecting shaft. A camera comprising the diaphragm device according to any one of claims 1 to 3.

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