Diaphragm mechanism and lens barrel

Abstract

To provide a diaphragm mechanism in which the operation stability of a diaphragm blade is improved, the degree of freedom in design is improved, and the size is reduced.SOLUTION: In a diaphragm mechanism comprising a diaphragm blade, a fixed member, and a rotating member, the diaphragm blade includes a first diaphragm blade group constituted by a plurality of first diaphragm blades and a second diaphragm blade group constituted by a plurality of second diaphragm blades. The first diaphragm blade has a fixed dowel and a moving dowel, one of the fixed member and the rotating member has a fitting hole into which the fixed dowel is fixed, the other of the fixed member and the rotating member has a cam groove that engages with the moving dowel, and the second diaphragm blade has an insertion hole through which the moving dowel is inserted. A positional relation between the moving dowel and the cam groove is changed by rotation of the rotating member, and the diaphragm blade is driven to open and close.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an aperture mechanism and a lens barrel equipped with an aperture mechanism. [Background technology]

[0002] Conventionally, it has been desirable for the aperture shape of an aperture mechanism to be as close to circular as possible, and multiple aperture blades are often used to form a nearly circular aperture. The multiple aperture blades are arranged overlapping each other in an annular shape. Furthermore, the size of the aperture shape can be changed by rotating a rotatable drive ring.

[0003] Generally, in an aperture mechanism in which multiple aperture blades are arranged in an overlapping ring around the optical axis, as the aperture is narrowed (i.e., the aperture shape becomes smaller), the aperture blades warp up near the aperture shape. When the aperture blades warp up, there is a risk that they may interfere with the lens adjacent to the aperture mechanism. Specifically, contact with the lens may damage the coating on the lens surface.

[0004] Therefore, in conventional diaphragm devices, the diaphragm mechanism and lenses must be positioned taking into account the space required for the amount of curvature of the diaphragm blades, which places constraints on optical design and is disadvantageous in terms of miniaturizing the lens barrel.

[0005] Patent Document 1 discloses a light amount adjusting device that is provided with a sloped portion for holding down the diaphragm blades in the direction opposite to the direction of the blades rising, as a method for suppressing the blades from rising up.

[0006] Patent Document 2 discloses a light amount adjusting device in which the amount of warping is reduced by lengthening the diaphragm blades so that they do not protrude from the inner diameter of the aperture member.

[0007] Patent Document 3 discloses a blade drive device that has double diaphragm blades and prevents the blades from overlapping with each other, resulting in a weaving-up effect. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-8853 [Patent Document 2] Japanese Patent Publication No. 2020-134724 [Patent Document 3] Patent No. 6654640 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the light amount adjustment device described in Patent Document 1 has a problem in that the rising of the diaphragm blades changes depending on the attitude of the lens barrel, and the effect of the abutting sloped portion in preventing the rising is limited.

[0010] Next, in the light amount adjusting device described in Patent Document 2, if the method of lengthening the diaphragm blades does not provide sufficient engagement at the end of the diaphragm blades, when the light amount adjusting device is subjected to an external shock, the tip of the diaphragm blade may fly out toward the inner diameter side, making it impossible to return by driving. Also, if sufficient engagement is to be ensured, there is a problem that the diaphragm mechanism as a whole becomes larger.

[0011] Finally, the blade drive device described in Patent Document 3 arranges two diaphragm mechanisms so that they rise up relative to each other, and by pressing down on each other, it prevents the aperture from rising up. However, increasing the number of diaphragm blades to obtain a good aperture shape increases the number of parts accordingly, which not only increases costs but also poses the problem of needing to secure storage space for the diaphragm blades in the optical axis direction.

[0012] The present invention has been made in view of the above circumstances, and has as its object to provide a compact diaphragm mechanism with improved operational stability of the diaphragm blades, increased freedom of design, and reduced size. [Means for solving the problem]

[0013] A first invention, which is a means for solving the above-mentioned problems, is an aperture mechanism having aperture blades, a fixed member, and a rotating member, wherein the aperture blades are made up of a first aperture blade group consisting of a plurality of first aperture blades and a second aperture blade group consisting of a plurality of second aperture blades, the first aperture blades have fixed dowels and movable dowels, one of the fixed member and the rotating member has a fitting hole that fits with the fixed dowel, the other of the fixed member and the rotating member has a cam groove that engages with the movable dowel, the second aperture blades have an insertion hole through which the movable dowel is inserted, and the positional relationship between the moving dowel and the cam groove changes as the rotating member rotates, thereby driving the aperture blades to open and close. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a compact diaphragm mechanism with improved operational stability of the diaphragm blades and increased design freedom. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is an exploded perspective view showing a throttle mechanism according to an embodiment of the present invention. [Figure 2] An enlarged view of an aperture blade according to an embodiment of the present invention. [Figure 3a] 1 is a plan view of an open state of a throttle mechanism according to an embodiment of the present invention; [Figure 3b] 1 is a plan view of a throttle mechanism according to an embodiment of the present invention in a throttled state; [Figure 4] 1 is a cross-sectional view of a throttle mechanism according to an embodiment of the present invention; [Figure 5] FIG. 10 is an explanatory diagram illustrating the amount of application of the throttle mechanism according to the embodiment of the present invention. [Figure 6] FIG. 10 is a plan view of the throttle mechanism according to the second embodiment of the present invention in a throttled state; DETAILED DESCRIPTION OF THE INVENTION

[0016] The best mode for carrying out the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

[0017] FIG. 1 is an exploded perspective view showing the main components of an aperture mechanism 1 according to an embodiment of the present invention. Note that FIG. 1 is simplified to show only the aperture mechanism 1 of the present invention. FIG. 2 is an enlarged view of a first blade 11 and a second blade 12 of an aperture blade 10 that constitutes the aperture mechanism 1. FIGS. 3(a) and 3(b) are plan views of the aperture mechanism 1. FIG. 4 is a cross-sectional view of the aperture mechanism 1. FIG. 5 is an explanatory diagram illustrating the engagement amount of the first blade that constitutes the aperture mechanism 1. In this embodiment, the direction along the optical axis of the aperture mechanism 1 is defined as the optical axis direction, and the direction along the outer periphery of the aperture mechanism 1 is defined as the circumferential direction, based on the aperture mechanism 1 that constitutes a lens barrel (not shown). Specifically, the optical axis direction in FIG. 1 is the direction along the optical axis that passes through the centers of the components arranged on the paper, and the circumferential direction is the circumference relative to the optical axis. In FIGS. 3 and 5, the optical axis direction is the front-to-back direction of the paper, and the circumferential direction is the horizontal direction of the paper. In FIG. 4, the optical axis direction is the up-to-down direction of the paper. Note that some reference numerals in the drawings have been omitted. Similar components are designated by the same reference numerals.

[0018] The configuration of the diaphragm mechanism 1 of this embodiment will be described using Figure 1. In the figure, the movable dowel 112 is shown by a dotted line because it is located on the surface of the first blade 11 that faces the fixed member 30. The fixed dowel 111 is located on the surface that faces the rotating member 20.

[0019] The aperture mechanism 1 of the present invention is generally used by being incorporated into a lens barrel, and the lens barrel (not shown) is attached to the imaging device and may be either replaceable or fixed, and includes an optical element (not shown) inside.

[0020] The diaphragm mechanism 1 includes diaphragm blades 10, a rotating member 20, and a fixed member 30.

[0021] The diaphragm blades 10 are made up of first blades 11 and second blades 12. The diaphragm mechanism 1 of the present embodiment has twelve first blades 11 and four second blades 12, but the numbers of first blades 11 and second blades 12 are not limited to this.

[0022] Figure 2 is an enlarged view of first blade 11 and second blade 12 that constitute diaphragm mechanism 1 of Figure 1, as seen from the fixed member 30 side. Note that the arc on the left side of first blade 11 shown in the figure is the inner circle side that forms first opening C1, and the lower side is the tip. Also, fixed dowel 111 in the figure is shown with a dotted line because it is located on the back side.

[0023] 3 is a plan view of the diaphragm mechanism 1 of FIG. 1 with the fixing member 30 removed, as seen from the fixing member 30 side. (a) shows the diaphragm mechanism 1 in an open state. (b) shows the diaphragm mechanism 1 in a state where it has been narrowed down by one step from the open state shown in (a).

[0024] The first blade 11 has a fixed dowel 111 and a movable dowel 112, with the fixed dowel 111 arranged on one surface and the movable dowel 112 arranged on the other surface. The second blade 12 has an insertion hole 121 through which the movable dowel 112 is inserted.

[0025] The insertion holes 121 of the second blade 12 will now be described. There are two types of insertion holes 121 of the second blade 12: first insertion holes 121a and second insertion holes 121b. In the present embodiment, the first insertion holes 121a are round holes, and the second insertion holes 121b are elongated holes. In both the first insertion holes 121a and the second insertion holes 121b, the movable dowels 112 of any two of the first blades 11 arranged in a ring shape are inserted into the first insertion holes 121a and the second insertion holes 121b, respectively, and the inserted movable dowels 112 engage with the cam grooves 31 of the fixed member 30. Therefore, when the rotating member 20 is rotated, the movable dowel 112 follows the cam groove 31, and the movement of the inserted second blade 12 can also be controlled by the shape and arrangement of the first insertion hole 121a and the second insertion hole 121b.

[0026] Furthermore, in the throttle mechanism 1 of the present embodiment, the first blade 11 is arranged in a ring shape so as to be knitted up on the side of the fixed member 30. Therefore, the second blade 12 is arranged on the side of the first blade 11 that is closer to the fixed member 30.

[0027] The rotary member 20 has a fitting hole 21. The fixing dowel 111 of the first blade 11 fits into the fitting hole 21.

[0028] The fixed member 30 has a cam groove 31. The cam groove 31 is engaged with the moving dowel 112 of the first blade 11.

[0029] This is the function of the diaphragm mechanism 1. To achieve the function of adjusting the amount of light passing through the diaphragm, it is necessary to change the diameter of the first opening C1 formed by the multiple first blades 11. Below, we will explain in detail how each member that makes up the diaphragm mechanism 1 moves when adjusting the amount of light.

[0030] To realize the light amount adjustment function of the aperture mechanism 1, it is necessary to rotate the rotary member 20. By operating an aperture ring or the like provided on the outer periphery of the lens barrel (not shown), the mechanically connected rotary member 20 rotates. Of course, even if not mechanically connected, the rotary member 20 may be rotated by a motor or the like based on the photographer's intention to change the aperture value.

[0031] When the rotating member 20 rotates, the rotation is transmitted to the first blade 11 via the fixed dowel 111 fitted into the fitting hole 21 of the rotating member 20. The transmitted rotation causes the first blade 11 to rotate around the optical axis. At this time, a movable dowel 112 is disposed on the surface of the first blade 11 opposite the fixed dowel 111. The movable dowel 112, which is inserted into the insertion hole 121 of the second blade 12, passes through the insertion hole 121 and engages with the cam groove 31 of the fixed member 30. Therefore, the movable dowel 112 moves along the cam groove 31, changing the distance between the movable dowel 112 and the optical axis. Therefore, when viewed with the fixed dowel 111 and the optical axis as references, the first blade 11 rotates around the fixed dowel 111 as its axis. Therefore, the first opening C1 formed by the multiple first blades 11 arranged in an annular shape changes, causing the diaphragm mechanism 1 to open and close.

[0032] At this time, the movable dowel 112 is inserted through the first circular insertion hole 121a and the elongated insertion hole 121b of the second blade 12. The position and orientation of the second blade 12 relative to the optical axis is determined by the position of the movable dowel 112 relative to the optical axis. As described above, when the distance between the movable dowel 112 and the optical axis changes as the rotating member 20 rotates, the position and orientation of the second blade 12 relative to the optical axis also changes, and as a result, the second opening C2 formed by the multiple second blades 12 arranged in an annular shape changes.

[0033] As described above, the position and attitude of first blade 11, which forms first opening C1, relative to the optical axis is determined by cam groove 31 of fixed member 30. In diaphragm mechanism 1 of the present invention, first opening C1, which is formed by multiple first blades 11, changes. As described above, the position and attitude of second blade 12 are also determined by cam groove 31 of fixed member 30. Second opening C2, which is formed by multiple second blades 12, changes in a similar manner. Note that the attitude of first blade 11 refers to the rotational attitude around fixed dowel 111 as an axis when fixed dowel 111 and the optical axis are used as references, and the attitude of second blade 12 refers to the rotational attitude around moving dowel 112 as an axis when movable dowel 112 and the optical axis are used as references.

[0034] Furthermore, since the movable dowel 112 that is not inserted into the insertion hole 121 is also engaged with the cam groove 31, the movement when rotation is transmitted from the rotating member 20 to the first blade 11 having the movable dowel 112 is the same as that of the first blade 11 having the movable dowel 112 that is inserted into the insertion hole 121.

[0035] 3a and 3b are plan views of first blade 11 and second blade 12 that constitute diaphragm mechanism 1 of the present invention, as seen from the optical axis direction fixing member 30 side. Fig. 3a shows the fully opened state, and Fig. 3b shows the state narrowed down by one step from the fully opened state. As mentioned above, first blade 11 and second blade 12 are each arranged in an annular shape, and therefore some of the reference numerals of the same components in Fig. 3 have been omitted.

[0036] As explained above and shown in FIG. 3, the aperture mechanism 1 of this embodiment uses 12 first blades 11. One movable dowel 112 is arranged on each first blade 11, so there are 12 movable dowels 112. On the other hand, there are four second blades 12. Each second blade 12 has two insertion holes, a first insertion hole 121a and a second insertion hole 121b, so eight of the 12 movable dowels 112 are inserted through them. It is not a problem if multiple insertion holes 121 are inserted through one movable dowel 112.

[0037] In the diaphragm mechanism 1 of the embodiment of the present application shown in Figure 3, after the 12 first blades are arranged in a ring shape, 12 movable dowels 112 are lined up around the optical axis as viewed from the fixed member 30 side. An arbitrary movable dowel 112 is inserted into the second insertion hole 121b of the first second blade 12, and the movable dowel 112 spaced clockwise is inserted into the first insertion hole 121a. Again, the clockwise movable dowel 112 is inserted into the second insertion hole 121b of the second second blade 12, and the movable dowel 112 spaced clockwise is inserted into the first insertion hole 121a. The same process is repeated for the third and fourth second blades 12, and the tip of the first insertion hole 121a of the fourth second blade 12 is positioned so that the rear end of the second insertion hole 121b of the first second blade 12 faces the fixing member 30, thereby arranging the four second blades 12 in a ring shape.

[0038] Although the aperture mechanism 1 in this embodiment has a combination of 12 first blades 11 and 4 second blades 12, the number of each blade can be changed to suit the optical design of the lens barrel. Because the number of second blades 12 does not depend on the number of first blades 11, it is possible to configure each of the first blades 11 and the second blades 12 with fewer blades than in this embodiment. This makes it possible to minimize the number of overlapping blades when the blades are retracted in the fully open state, which contributes to the miniaturization of the aperture mechanism 1.

[0039] Furthermore, even if the number of first blades 11 is increased to obtain a first opening C1 with a good shape, there is no need to increase the number of second blades 21. As a result, there is an effect that the number of parts and manufacturing costs can be reduced.

[0040] Next, the positional relationship between first blade 11 and second blade 12 when they move along cam groove 31 will be described. In diaphragm mechanism 1 of the present invention, as the opening area of ​​first opening C1 formed by first blade 11 decreases from Figure 3(a) to Figure 3(b), the opening area of ​​second opening C2 formed by second blade 12 also decreases. At this time, regardless of the state of the opening area of ​​first opening C1, the tip of first blade 11 is designed to always be located outside second opening C2.

[0041] In diaphragm mechanisms that adjust the amount of light by opening and closing a plurality of diaphragm blades arranged in a ring, such as the diaphragm mechanism 1 of the present invention, the phenomenon of the diaphragm blades warping up (the tips of the diaphragm blades weaving together) can occur. This can be particularly problematic when the first opening C1, which is the opening of the diaphragm mechanism 1, is narrowed down to a small aperture diameter (close to the minimum aperture area), as the amount of warping becomes large.

[0042] As described above, in the diaphragm mechanism 1 of the present invention, the tip of first blade 11 is always positioned outside second opening C2, so that second blade 12 forming second opening C2 physically holds down the tip of first blade 11 that tends to warp up. Therefore, regardless of the opening area of ​​first opening C1, it is possible to prevent first blade 11 from warping up. Furthermore, the diaphragm mechanism 1 of the present invention can prevent first blade 11 from flying out even when subjected to an external impact. This will be explained in detail below using Figures 4 and 5.

[0043] FIG. 4 is a cross-sectional view of aperture mechanism 1 cut along the optical axis. As described above, aperture mechanism 1, which is comprised of multiple aperture blades 10, receives an impact from the lens barrel (not shown) (in the direction of the white arrow in the figure), causing first blade 11 to bend as shown in FIG. 4. As a result, the tip of first blade 11, which had been positioned so as to overlap with fixed member 30 in the optical axis direction (hereinafter, "hook"), moves toward the inner diameter. In other words, when the tip of first blade 11 moves from the position indicated by arrow a to the position indicated by arrow b in FIG. 4, the hook at the tip of first blade 11 is released (i.e., the tip of first blade 11 no longer overlaps with fixed member 30 in the optical axis direction), causing first blade 11 to protrude. This may occur regardless of the state of first opening C1.

[0044] In conventional aperture mechanisms, the tips of the aperture blades are attached to fixed members, so the area over which the blades can be attached is fixed. However, as the aperture value increases, the aperture blades narrow down, which causes a state in which the blades are less attached, making it difficult to ensure that the blade tips always have sufficient attachment. As a result, there is a concern that the tips of the aperture blades may fly out due to external impact.

[0045] However, if a sufficient amount of application is to be ensured in order to prevent the diaphragm blades from protruding, the diaphragm mechanism itself will end up becoming larger.

[0046] 5 is an explanatory diagram illustrating the engagement amount of first blade 11 of diaphragm mechanism 1 of the present invention. An explanation will be given using one specific one of the first blades 11 that make up diaphragm mechanism 1. The tip of this first blade 11 is located at the 6 o'clock position, and in the configuration of a conventional diaphragm mechanism, the engagement amount of diaphragm blade 11 would be Z2 because the engagement end of diaphragm blade 11 is fixed member 30. On the other hand, in the configuration of diaphragm mechanism 1 of the present invention, the engagement end of first blade 11 is second blade 12, so the engagement amount is Z1.

[0047] 5, it can be seen that the engagement amount Z1 of first blade 11 of diaphragm mechanism 1 of the present invention is greater than the engagement amount Z2 of a conventional diaphragm mechanism. Furthermore, because second blade 12 follows cam groove 31 as described above, the second opening C2 formed by second blade 12 also becomes smaller as first blade 11 is narrowed, so it is possible to always ensure the engagement amount regardless of the size of first opening C1 formed by first blade 11.

[0048] As described above, in the diaphragm mechanism 1 of the present invention, the tip of first blade 11 is always pressed down by second opening C2, which has the effect of preventing first blade 11 from warping up without requiring the diaphragm mechanism 1 itself to be made larger in order to ensure the engagement of first blade 11, and also has the effect of improving the operational stability of the diaphragm mechanism 1 because first blade 11 is prevented from flying out in the event of an impact regardless of the attitude of the lens barrel.

[0049] In the aperture mechanism 1 of the present embodiment, the second blade 12 is disposed on the fixing member 30 side of the first blade 11, but in order to achieve the above-mentioned effect, the second blade 12 needs to be disposed in the direction in which the first blade 11 warps upward.

[0050] Furthermore, up until now, the diaphragm mechanism 1 of this embodiment has been configured such that the fitting hole 21 that fits with the fixed dowel 111 is disposed in the rotating member 20, and the cam groove 31 that engages with the movable dowel 112 is disposed in the fixed member 30. However, there is no problem with a configuration in which the cam groove 31 that engages with the movable dowel 112 is disposed in the rotating member 20, and the fitting hole 21 that fits with the fixed dowel 111 is disposed in the fixed member 30.

[0051] Next, as can be seen from the drawings, in the present invention, first insertion hole 121a is a round hole and second insertion hole 121b is an elongated hole. However, the round hole and the elongated hole may be connected to form one hole. As long as first insertion hole 121a and second insertion hole 121b can fulfill the role of second blade 12, which is to prevent first blade 11 from warping up and popping out by engaging with movable dowel 112 as described above, the shape and number of insertion holes 121 are not important.

[0052] In the present embodiment, each second blade 12 has two movable dowels 112 inserted therethrough. However, if only one movable dowel 112 is inserted into each second blade 12, the second blade 12 becomes rotatable around the inserted movable dowel 112, resulting in an unstable position and posture. If the second blade 12 rotates unintentionally, the tip of the second blade 12 may protrude into the first opening shape formed by the first blade 11, potentially interfering with the original function of the diaphragm mechanism 1. Therefore, the inner diameter of the second blade 12 needs to be increased radially to account for vibration in the rotational direction. However, increasing the inner diameter of the second blade 12 reduces the amount of engagement of the tip of the first blade 11, thereby preventing the second blade 12 from fully functioning.

[0053] In this embodiment, each second blade 12 has two movable dowels 112 inserted therethrough. Since the posture is determined by the dimensional relationship between the hole and the two inserted movable dowels 112, precision is easily achieved. As a result, it is possible to minimize the inner diameter of the second blade, which has the advantage of making it easier to ensure the amount of engagement of the tip of the first blade 11.

[0054] 3(a) and 3(b), unlike first blade 11, in which the tip moves toward the inner diameter side (toward the optical axis) as the aperture is narrowed, second blade 12 may move not only its tip but also the entire second blade 12 toward the inner diameter side (toward the optical axis). On the other hand, like first blade 11, there may also be no problem if the tip of second blade 12 rotates toward the optical axis side.

[0055] The aperture mechanism 1 of the present invention does not require space to avoid interference with the lens when the first blade 11 warps upward, which increases the freedom of optical design and contributes to the miniaturization of lens barrels equipped with the aperture mechanism 1.

[0056] The aperture mechanism 1 of the present invention is a simple configuration in that it adds second blade 12 to the configuration of a typical aperture mechanism consisting of rotating member 20, first blade 11, and fixed member 30. The rotating member 20, first blade 11, and fixed member 30 have the same configuration as a typical aperture mechanism, so there are no problems. As mentioned above, second blade 12 is provided with first insertion hole 121a and second insertion hole 121b through which movable dowel 112 passes, which is mechanically designed so that second blade 12 moves in accordance with the movement of movable dowel 112 along cam groove 31, so that second opening C2 formed by second blade 12 presses against the tip of first blade 11, thereby realizing the effects unique to the present invention.

[0057] Furthermore, in diaphragm mechanism 1 of the present invention, first blade 11 has fixed dowel 111 and movable dowel 112, and second blade 12 has only an insertion hole through which movable dowel 112 passes. Therefore, after the problem of the first blade warping up in a general diaphragm mechanism is discovered as described above, it is possible to achieve the effects of the present invention by simply adding the second blade without performing any additional processing on the general diaphragm mechanism.

[0058] As described above, the aperture mechanism 1 of the present invention does not require the provision of a shape that serves as a fulcrum for the second blade 12 or the lengthening of the cam groove 31, and there is no need to reserve space to arrange these elements, thereby achieving the effect of realizing freedom in the design of the aperture mechanism 1 and making it more compact.

[0059] Example 2 A diaphragm mechanism 1 of Example 2, which is an alternative to the diaphragm mechanism 1 described up to this point (hereinafter referred to as the diaphragm mechanism of Example 1), will be described using Figure 6. Similar to Figures 3a and 3b, Figure 6 is a plan view of first blade 11 and second blade 12 that constitute diaphragm mechanism 1 of Example 2, viewed from the optical axis direction fixing member 30 side. Note that diaphragm mechanism 1 of Example 2 shown in Figure 6 is in a state where it is one stop narrower than the fully open state.

[0060] The diaphragm mechanism 1 of Example 2 shown in FIG. 6 is composed of, from the object side, a rotating member 20, a first blade 11, a second blade 12, and a fixed member 30, and has a configuration similar to that of the diaphragm mechanism 1 of Example 1 shown in FIG. 3a and elsewhere. However, the diaphragm blades 10 of the diaphragm mechanism 1 of Example 2 are composed of eleven first blades and four second blades. The difference between the diaphragm mechanisms 1 of Examples 1 and 2 is the second blade 12. As described above, the second blade 12 of Example 1 has multiple insertion holes, including the round first insertion hole 121a and the elongated insertion hole 121b. On the other hand, the second blade 12 of Example 2 has only one insertion hole 121 through which the movable dowel 112 passes.

[0061] In the diaphragm mechanism 1 of Example 2, since there is only one movable dowel 112 inserted into each second blade 12, the second blade 12 is rotatable around the movable dowel 112, which makes the position and posture unstable. Therefore, in the diaphragm mechanism 1 of Example 2, a movable dowel 112 different from the movable dowel 112 inserted into the second blade 12 is in contact with the outer edge of the second blade 12. Specifically, a description will be given using the second blade 12 located at the 4 o'clock position as shown in FIG. 6. The second blade 12 has one insertion hole 121, through which the movable dowel 112 is inserted. The outer edge of the second blade 12 is in contact with two movable dowels 112. The two movable dowels 112 that contact at the outer edge are arranged so as to contact the outer edges of the second blade 12 that are separated by a straight line (dotted line in the drawing) that connects the optical axis and the movable dowels 112 that are inserted into the insertion holes 112. As a result, the position and posture of the second blade 12 are restricted by the movable dowels 112 that contact at the outer edge, and the second blade is also prevented from rotating around the movable dowel 112 that is inserted.

[0062] Also, it has been described that the two movable dowels 112 in contact with the outer edge of second blade 12 are arranged so as to be in contact with the outer edge of second blade 12 on one side separated by a straight line connecting movable dowel 112 inserted through second blade 12 and the optical axis. However, in diaphragm mechanism 1 of Example 2, by forming second blade 12 in a shape that restricts rotation about movable dowel 112 inserted through insertion hole 21 as an axis, the two movable dowels 112 in contact with the outer edge of second blade 12 may be arranged on one side of the outer edge of second blade 12 separated by a straight line connecting movable dowel 112 inserted through second blade 12 and the optical axis.

[0063] In the above description of Example 2, the second blade 12 and the movable dowels 112 located on the outer edge are in contact, but there is no problem even if they are not in contact as long as the movable dowels 112 fulfill their role of preventing rotation of the second blade and regulating its position and posture. Also, the outer edge of the second blade 12 is the area along the outer periphery of the second blade 12. Furthermore, the number of movable dowels 112 located on the outer edge of the second blade 12 is not limited to two and can be increased or decreased without any problem.

[0064] The configuration disclosed in the diaphragm mechanism 1 of the first embodiment has the advantage of easily achieving precision, since the posture is determined by the dimensional relationship between the movable dowel 112 inserted into the round hole and the elongated hole. In addition, since precision can be easily achieved, it also has the advantage of easily ensuring the amount of engagement of the tip of the first blade 11.

[0065] The configuration disclosed in diaphragm mechanism 1 of Example 2 makes it possible to simplify the shape of second blade 12. In addition, second blade 12 is not located on the outer diameter side of movable dowel 112 except for round insertion hole 121, which has the effect of being advantageous for making diaphragm mechanism 1 more compact. [Explanation of symbols]

[0066] 1 Aperture mechanism 10 aperture blades 11 First Feather 111 Fixed dowel 112 Movable dowel 12 Second Feather 121a First insertion hole 121b Second insertion hole 20 Rotating member 21 Fitting hole 30 Fixing member 31 Cam groove C1 1st opening C2 2nd opening

Claims

1. Diaphragm blades, fixed members, and rotating members In a throttling mechanism having The aperture blades are a first diaphragm blade group consisting of a plurality of first diaphragm blades and a second diaphragm blade group consisting of a plurality of second diaphragm blades; The first diaphragm blade is It has a fixed dowel and a movable dowel, one of the fixed member and the rotating member has a fitting hole into which the fixed dowel fits, the other of the fixed member and the rotating member has a cam groove that engages with the moving dowel, The second diaphragm blade is an insertion hole through which the movable dowel is inserted; a diaphragm mechanism in which the positional relationship between the moving dowel and the cam groove changes as the rotating member rotates, thereby driving the diaphragm blades to open and close;

2. 2. The aperture mechanism according to claim 1, wherein the tip of the first aperture blade is positioned outside the aperture shape formed by the second aperture blade group.

3. 2. The aperture mechanism according to claim 1, wherein a plurality of the movable dowels are inserted into the second aperture blade.

4. 3. The aperture mechanism according to claim 2, wherein a plurality of the movable dowels are inserted into the second aperture blade.

5. 2. The diaphragm mechanism according to claim 1, wherein the second diaphragm blade group is arranged in a weaving direction of the first diaphragm blade group in the optical axis direction.

6. 2. The aperture mechanism according to claim 1, wherein the second diaphragm blade, one of the movable dowels being inserted into the insertion hole, is positioned on an outer edge of the second diaphragm blade and is restricted by the movable dowel that is different from the movable dowel that is inserted into the insertion hole.

7. A lens barrel comprising the diaphragm mechanism according to any one of claims 1 to 6.

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