Diaphragm device and image pickup apparatus

Abstract

To provide a diaphragm device in which warp of diaphragm blades is suppressed, and to provide an imaging apparatus.SOLUTION: An aperture forming member 107 provided with a fixed aperture forming an optical path, a plurality of diaphragm blades 105 moving into and out of the optical path, a plurality of transverse blades 106 having distal ends crossing the light passage aperture, and a drive ring 104 driving the plurality of diaphragm blades 105 and the plurality of transverse blades 106, wherein the plurality of diaphragm blades 105 each have a rotation center portion and a distal end portion away from the rotation center portion, and the plurality of transverse blades 106 each have a rotation center portion and a distal end portion away from the rotation center portion, the plurality of diaphragm blades 105 are annularly overlapped with each other on the front and rear sides around the light passing opening to form a diaphragm blade group in which the tip parts of the plurality of diaphragm blades 105 are arranged so as to be knitted in one direction, and the tip parts of the plurality of cross blades 106 are overlapped with the peripheral edge part of the fixed opening in the optical path direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an aperture device mounted in an optical device such as an imaging device or an interchangeable lens, and to an imaging device. [Background technology]

[0002] The shape of the aperture formed in the aperture device as a light passage opening is preferably as close to circular as possible, and in order to form an aperture that is close to circular, three or more aperture blades (light amount adjustment blades) are often used. Also, a polygonal aperture that is close to circular is formed by rotating the multiple aperture blades using a rotating member that can rotate around a fixed aperture formed in a base member (aperture forming member). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-99022 Summary of the Invention [Problem to be solved by the invention]

[0004] In the diaphragm device of Patent Document 1, overlapping of the diaphragm blades causes the tips of the diaphragm blades to tilt up in the optical axis direction, and the diaphragm position changes in the optical axis direction as a small diameter diaphragm opening is formed. [Means for solving the problem]

[0005] In order to solve the above problem, the light quantity adjustment device of the present invention comprises an aperture forming member having a fixed opening that forms an optical path, a plurality of aperture blades that enter and exit the optical path, a plurality of transverse blades whose tips cross the light passing opening, and a drive ring that drives the plurality of aperture blades and the plurality of transverse blades, wherein the plurality of aperture blades have a rotation center and a tip end away from the rotation center, and the plurality of transverse blades have a rotation center and a tip end away from the rotation center, and the plurality of aperture blades and the plurality of transverse blades overlap each other in a ring shape around the light passing opening, forming a group of aperture blades in which the tip ends are arranged so as to weave in one direction, and the transverse blades cross the fixed opening, and the tip ends overlap the peripheral portion of the fixed opening in the optical path direction. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a light amount adjusting device in which the weaving of the diaphragm blades is suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an exploded perspective view of a diaphragm device according to a first embodiment. [Figure 2] Perspective view of the aperture device (A) Cover member side (B) Cam member side [Figure 3] Front view of the aperture device (A) Full aperture (B) Medium aperture (C) Small aperture [Figure 4] Front view of the aperture device (cam member not shown) (A) Full aperture state (B) Medium aperture state (C) Small aperture state [Figure 5] Front view of the aperture device (cam member and cross blades not shown) (A) Full aperture state (B) Medium aperture state (C) Small aperture state [Figure 6] Front view of the aperture device (cam member, two cross blades, six aperture blades not shown) (A) Full aperture state (B) Medium aperture state (C) Small aperture state [Figure 7] Front view of the aperture device (cam member, seven aperture blades, and two cross blades not shown) [Figure 8] Perspective view of aperture blades [Figure 9] Perspective view of the crossing blade [Figure 10] Cross section of throttle device (fully open) [Figure 11] Cross-section of aperture device (small aperture state) [Figure 12] Cross-sectional view of a conventional aperture device (small aperture state) [Figure 13] Schematic diagram of an optical device equipped with the diaphragm device of this embodiment. [Figure 14] Schematic diagram of an optical device equipped with a conventional aperture device DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0009] <Embodiment 1> 1(A) and 1(B) are exploded perspective views of an aperture device according to a first embodiment of the present invention.

[0010] 2(A) and (B) are perspective views of the aperture stop device according to the first embodiment.

[0011] 1, the optical axis center 100 of the diaphragm device is indicated by a dashed line. A driving unit 101 that operates the diaphragm device may be, for example, a stepping motor, a galvanometer, etc. A pinion 103 is attached to the rotation axis of this driving unit 101.

[0012] The cover member 102, which is an opening forming member having an opening 102a formed in the center, is formed by, for example, resin molding in this embodiment.

[0013] In this embodiment, the rotating member 104 is, for example, a circular member formed by resin molding, and is an opening-forming member (rotating member) having a circular opening 104a formed in the center thereof, which serves as a path for light to pass through.

[0014] The rotating member 104 has a plurality of drive holes 104b and a sliding surface 104e with which the aperture blades 105, which will be described later, slide. The sliding surface 104e is preferably circular, or has an axisymmetric shape in accordance with the number of blades, so that the plurality of aperture blades can slide over the surface under the same conditions. The rotating member 104 also has a gear portion serving as a driven portion 104f. The driven portion 104f meshes with the pinion 103. The rotational force generated by the driving portion 101 is transmitted from the pinion 103 to the driven portion 104f, thereby rotating the rotating member 104. For example, in this embodiment, the rotational force of the driving portion 101 is transmitted directly from the pinion 103 to the rotating member 104. However, an intermediate gear (including a reduction gear, etc.) may be used between the pinion 103 and the rotating member 104. Although not shown, a light-shielding portion is provided on the rotating member 104, and the light-shielding portion moves in and out of a slit in a photointerrupter or the like, making it possible to detect positions such as the initial position of the diaphragm device. In addition, by providing a stopper on the rotating member 104, the angle of rotation can be restricted by contact with the stopper portion of the cover member 102.

[0015] In this embodiment, a plurality of (nine) aperture blades 105 are arranged in a ring shape to surround an opening through which light passes. Each aperture blade 105 is formed with an engagement shaft 105b and a cam shaft 105c, which are driven parts. Such aperture blades 105 may be made, for example, by forming an axis on a PET sheet material or the like and then pressing it, or by resin molding. Although this embodiment is configured with nine aperture blades, the number of aperture blades may be any number greater than or equal to three. The maximum opening of the portion through which light passes may be determined by an opening 104a in the rotating member, an opening 102a in the cover member, or an opening 107a in the cam member (described later), or by an opening 105a formed at the ends of multiple aperture blades.

[0016] In this embodiment, for example, a plurality of (three) transverse blades 106 are arranged in an annular shape so as to surround an opening through which light passes. Each transverse blade 106 is formed with an engagement hole 106b and a cam groove 106c, which are driven parts. Such a transverse blade 106 may be made, for example, by pressing a PET sheet material or the like, or may be made by resin molding or the like. Furthermore, although this embodiment is configured with three transverse diaphragm blades, the number of transverse blades may be any number.

[0017] The cam member 107 houses the above-mentioned multiple diaphragm blades 105 and multiple crossing blades 106 between it and the rotating member 104, and forms a blade chamber in which the blades move between it and the rotating member 104. That is, the multiple diaphragm blades 105 and multiple crossing blades 106 move (drive) in the blade chamber (space) formed by the rotating member 104 and the cam member 107 as the rotating member 104 rotates. An opening 107a communicating with the opening 102a of the cover member is formed in this cam member 107, and it serves as an opening forming member. The cam member 107 may be formed by resin molding or the like.

[0018] The engagement shaft 105b of the diaphragm blade engages with the drive hole 104b of the rotating member. The pinion 103 rotates, applying force to the driven part 104f of the rotating member, causing the rotating member 104 to rotate. Then, a driving force is applied from the drive hole 104b of the rotating member to the engagement shaft 105b of the diaphragm blade, driving the diaphragm blade 105. At this time, the cam shaft 105c of the diaphragm blade engages with the engagement part 107c of the cam member, so the cam groove 107c causes the diaphragm blade 105 to move in and out of the opening 107a of the cam member. This allows the multiple diaphragm blades 105 to adjust the diaphragm shape within the opening 107a of the cam member, making it possible to adjust the amount of light passing through.

[0019] The engagement holes 106b of the crossing blades engage with the engagement shafts 105c of the diaphragm blades, and as the diaphragm blades 105 are driven, the engagement holes 106b of the crossing blades move radially through the opening 107a of the cam member. At this time, the engagement shafts 105b of different diaphragm blades engage with the cam grooves 106c of the crossing blades, so the cam grooves 106c allow the crossing blades 106 to move in and out of the opening 107a of the cam member. However, at this time, the tip 106e of the crossing blades always moves outside the opening 107a of the cam member, and the crossing blades 106 are in a state of crossing the opening 107a of the cam member.

[0020] It is desirable that the number of diaphragm blades 105 is an integer multiple of the number of traverse blades 106. This is to allow the multiple diaphragm blades 105 to slide in contact with each other under the same conditions as much as possible. For example, in this embodiment, the number of traverse blades 106 is three, while the number of diaphragm blades 105 is three times as many, that is, nine.

[0021] FIG. 3(A) shows the aperture of the aperture device in a fully opened state, FIG. 3(B) shows the aperture in an intermediate state, and FIG. 3(C) shows the aperture in a small state.

[0022] 4 shows the state in which the cam member 107 has been removed, with FIG. 4(A) showing the fully opened aperture, FIG. 4(B) showing the intermediate aperture, and FIG. 4(C) showing the small aperture.

[0023] 5 shows the state in which the cam member 107 and the multiple cross blades 106 have been removed, with FIG. 5(A) showing the fully opened iris, FIG. 5(B) showing the intermediate iris, and FIG. 5(C) showing the small iris.

[0024] Figure 6 shows the state where the cam member 107, two transverse blades 106, and six diaphragm blades 105 have been removed, with Figure 6(A) showing the fully open diaphragm state, Figure 6(B) showing the intermediate diaphragm state, and Figure 6(C) showing the small diaphragm state.

[0025] Fig. 7 shows the state in which the cam member 107, seven diaphragm blades 105, and two cross blades 106 have been removed in the fully open state. Fig. 8 shows a perspective view of the diaphragm blades 105. Fig. 9 shows a perspective view of the cross blades 106. Fig. 10 shows a cross-sectional view of the first embodiment. Fig. 11 shows a cross-sectional view in the small aperture state.

[0026] This embodiment is effective in reducing the amount of weaving between the aperture blades. The multiple aperture blades 105 and the multiple crossing blades 106 are arranged in a ring shape so that the front and back surfaces of adjacent blades overlap. When the aperture blade 105 is driven from a fully open state to a small aperture state, weaving occurs, and the tip 105e of the aperture blade tends to protrude in the direction A. However, because the end face 106d of the crossing blade 106 moves around the periphery of the aperture blade opening 105a, the aperture blade 105 is pressed by the crossing blade 106 near the tip 105e of the aperture blade. This reduces the amount of weaving between the aperture blades.

[0027] Figure 12 shows a cross-sectional view of a conventional small aperture state. In the conventional technology, the aperture blades are pressed by a cam member that is distant from the tip of the aperture blade, so the braiding of the aperture blades protrudes in one direction when the aperture is in a small aperture state. In this embodiment, the braiding of the blade tip from the cam member 107 is very small, which is effective in making the device thinner and more compact.

[0028] Furthermore, when the diaphragm device of this embodiment is incorporated into an optical device such as a lens barrel, the distance between the diaphragm device and the lens can be reduced. Fig. 13 is a diagram showing the diaphragm device of this embodiment incorporated between lenses in a lens barrel. Meanwhile, Fig. 14 is a diagram showing a conventional diaphragm device incorporated into a lens barrel. This figure shows a state in which the multiple diaphragm blades 105 have been knitted by a knitting amount h compared to Fig. 9. As can be seen from these figures, this embodiment allows the distance between the diaphragm device and the lens to be reduced.

[0029] Because the diaphragm blades of this embodiment are not knitted, it is possible to place the lens extremely close to the diaphragm device. In the case of conventional diaphragm devices, the lens must be positioned taking into account the space required for the blade knitting amount h, which is disadvantageous in terms of slimming down the device. In this embodiment, the diaphragm blade knitting amount is extremely small compared to conventional diaphragm devices. In other words, the diaphragm device of this embodiment can reduce the distance to the lens, thereby increasing the degree of freedom in optical design, contributing to improved optical characteristics and smaller, thinner optical devices.

[0030] Furthermore, in the diaphragm device of this embodiment, there is little fluctuation in the aperture formation position in the optical axis direction. In conventional diaphragm devices, as the diaphragm diameter is reduced, the diaphragm blades tend to knit, and the position of the aperture formation position in the optical axis direction tends to move in the direction of the diaphragm blade knitting. When the diaphragm diameter is small, the diaphragm aperture formation position sometimes protrudes from the cover member. In this embodiment, from maximum aperture to minimum aperture, the diaphragm aperture formation position is formed between the base member 4 and the cover member 8. This is because the tip 106e of the crossing blade crosses the opening 107a, causing the diaphragm blade 106 to press the diaphragm blade 105 near the opening 105a, preventing the blade tip from knitting up as occurs in conventional technology. [Explanation of symbols]

[0031] 101 Aperture drive unit 102 Cover member (opening forming member) 103 Pinion gear 104 Rotating member 105 aperture blades 106 Cross Feather 107 Cam member

Claims

1. an aperture forming member provided with a fixed aperture that forms an optical path; a plurality of aperture blades that move in and out of the optical path; a plurality of transverse blades whose tips cross the light passage opening; a drive ring that drives the plurality of aperture blades and the plurality of transverse blades, the plurality of aperture blades have a rotation center and a tip portion spaced apart from the rotation center, The plurality of transverse blades have a rotation center and a tip portion spaced from the rotation center, The diaphragm device is characterized in that the transverse blade traverses the fixed opening, and the tip portion overlaps the peripheral portion of the fixed opening in the optical path direction.

2. The aperture device of claim 1, The plurality of diaphragm blades and the plurality of transverse blades are arranged around the light passage opening, An aperture device characterized by forming a group of aperture blades arranged in a unidirectional weave by overlapping the front and back of each other in a ring shape.

3. The aperture device of claim 1, The plurality of aperture blades have an engagement shaft and a cam shaft, The plurality of crossing blades have engagement holes and cam grooves, The aperture device is characterized in that the engagement holes and the cam grooves engage with different cam shafts among the plurality of aperture blades.

4. The aperture device of claim 1, An aperture device characterized in that the number of aperture blades is an integer multiple of the number of transverse blades.

5. An optical instrument comprising the diaphragm device according to any one of claims 1 to 4.

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