Light quantity adjusting device and optical apparatus

Abstract

To provide a light quantity adjusting device capable of high-speed operation while keeping the strength of a driving ring.SOLUTION: A light quantity adjusting device includes: a base member 50 having a fixed aperture through which light passes and a plurality of cam groove portions; a plurality of diaphragm blades 10 arranged in a circumferential direction of the fixed aperture and forming a variable aperture through which the light passes; and a driving ring 20 that rotates the plurality of diaphragm blades 10 so as to change a size of the variable aperture by rotating in the circumferential direction of the fixed aperture and transmitting driving force to the diaphragm blades 10. In the light quantity adjusting device, a driving source portion 1, which rotationally drives the driving ring 20, is supported by a pressing member, a blade support portion of the driving ring 20 has a hole shape 23, and a radial support portion 26 is continuous around the entire circumference.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a light amount adjusting device, which is mounted on an optical device such as a camera or an interchangeable lens, and is also called a light amount adjusting device. [Background technology]

[0002] The light amount adjusting device described above is required to operate quickly and smoothly. In conventional light quantity adjusting devices such as those described in Patent Document 1 and Patent Document 2, a drive ring is rotated around a fixed aperture to rotate multiple diaphragm blades in the opening and closing direction, and the light quantity is adjusted by changing the size of the diaphragm aperture (variable aperture) formed by the multiple diaphragm blades. Such light quantity adjusting devices are also called iris-type light quantity adjusting devices.

[0003] In the light amount adjusting device of Patent Document 2, the blade surface of each diaphragm blade opposite to the base plate side is supported by a drive ring, and some support portions have holes formed therein.

[0004] The drive ring is also formed with a radial support portion that protrudes toward the presser plate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-179169 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-145929 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, in the light intensity adjustment device of Patent Document 1, a blade support portion is provided on the drive ring, and a recess is provided on the inner peripheral side of the radial support portion that is connected around the entire circumference of the surface opposite the blade surface, and no hole shape is provided on the blade surface side.

[0007] In this case, the drive ring is heavy, and the drive ring and the aperture blades come into contact with each other, causing friction and increasing resistance, resulting in a sliding load.

[0008] On the other hand, in the light amount adjusting device of Patent Document 2, the radial support portion of the drive ring is not continuous all the way around, and holes are formed in the blade surfaces of the blade support portions provided on the inner periphery side of the radial support portion.

[0009] In this case, since the radial support portion of the drive ring is not continuous all the way around, it may deform during operation, making it difficult to maintain strength. [Means for solving the problem]

[0010] In order to solve the above problem, the light intensity adjustment device of the present invention is a light intensity adjustment device having a base member having a fixed opening through which light passes, a plurality of diaphragm blades arranged circumferentially around the fixed opening to form a variable opening through which the light passes, and a drive ring that rotates circumferentially around the fixed opening to transmit a driving force to the diaphragm blades, thereby rotating the plurality of diaphragm blades to change the size of the variable opening, and is characterized in that the blade support portion of the drive ring has a hole shape, and the radial support portion of the drive ring is connected all the way around. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a light amount adjusting device that allows high-speed operation while maintaining the strength of the drive ring. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an exploded perspective view of a light amount adjusting device according to a first embodiment of the present invention. [Figure 2] FIG. 3 is a perspective view of an aperture blade in the light amount adjustment device according to the first embodiment. [Figure 3] FIG. 3 is a perspective view of a drive ring in the light amount adjustment device according to the first embodiment. [Figure 4] FIG. 4 is a rear view of the drive ring in the light amount adjustment device according to the first embodiment. [Figure 5] FIG. 4 is a perspective view of a blade support portion of a drive ring in an open state in the light amount adjustment device according to the first embodiment. [Figure 6] FIG. 4 is a perspective view of a blade support portion of a drive ring in a small aperture state in the light amount adjustment device according to the first embodiment. [Figure 7] FIG. 2 is a cross-sectional view of the light amount adjusting device according to the first embodiment. [Figure 8] FIG. 1 is a perspective view of a light amount adjustment device according to a first embodiment. [Figure 9] FIG. 10 is a diagram showing Example 1 of the surface fiber state of a drive ring in a conventional light amount adjustment device. [Figure 10] 4A and 4B are diagrams showing the surface fiber state of a drive ring in the light amount adjustment device according to the first embodiment. [Figure 11] 10A and 10B are diagrams showing Example 2 of the surface fiber state of the drive ring in the light amount adjustment device. [Figure 12] 1 is a schematic diagram of an imaging device equipped with a light amount adjustment device according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] Example 1 Fig. 1 shows an exploded view of an iris-type light amount adjusting device as a light amount adjusting device according to a first embodiment of the present invention. Fig. 8 shows the assembled state of the light amount adjusting device according to this embodiment. Note that although a light amount adjusting device will be described here, a shutter device or a light amount adjusting device having a shutter function is also included in the light amount adjusting device according to the first embodiment of the present invention.

[0015] The light amount adjusting device of this embodiment includes an actuator 1, a presser plate (presser member) 40, a sheet member 30, a drive ring 20, a plurality of diaphragm blades 10, a base plate (base member) 50, and a photointerrupter 3.

[0016] The actuator 1 is an electromagnetic actuator such as a stepping motor. A pinion gear 2 that rotates and drives a drive ring 20 is attached to the output shaft of the actuator 1. The actuator 1 and pinion gear 2 form a drive source unit.

[0017] The photointerrupter 3 is used as a sensor for detecting the initial position of the drive ring 20. The actuator 1 is attached to the retainer plate 40 with a screw 61.

[0018] Reference numeral 5 denotes the central axis of the light amount adjustment device, which coincides with the optical axis of the imaging device when the light amount adjustment device is mounted on an imaging device described below. In the following description, the direction parallel to this central axis 5 is referred to as the thrust direction. The presser plate 40, drive ring 20, sheet member 30, multiple diaphragm blades 10, and base plate 50 are stacked in this order in the thrust direction. That is, the drive ring 20 is disposed on the opposite side of the diaphragm blades 10 from the base plate 50, and the presser plate 40 is disposed on the opposite side of the diaphragm blades 10 and drive ring 20 from the base plate 50. The direction and plane perpendicular to the thrust direction are referred to as the radial direction and radial plane, respectively.

[0019] A plurality of diaphragm blades 10 are arranged in the circumferential direction of a fixed opening 54 formed in the base plate 50. In this embodiment, eleven diaphragm blades 10 are used. Note that the number of diaphragm blades is not limited to eleven, and may be any other number.

[0020] Figure 2 shows an enlarged view of one diaphragm blade 10. Diaphragm blade 10 is arranged so as to be approximately parallel to the radial plane and has a flat blade portion with a light-blocking function, and a drive pin 11 and a cam pin 12 that protrude from the blade portion in opposite directions in the thrust direction. The drive pin 11 and the cam pin 12 are located at different positions in the radial plane.

[0021] 3 shows an enlarged view of the drive ring 20. The drive ring 20 has a light passage opening 24 at its center, and further has a blade support portion 31 provided in a ring shape in the circumferential direction around the light passage opening.

[0022] As shown in FIG. 4, the blade support portion 31 of the drive ring 20 is formed with drive holes 23 into which the drive pins 11 of the eleven diaphragm blades 10 are inserted and engaged.

[0023] Furthermore, a gear portion 25 that meshes with the pinion gear 2 is formed on a part of the outer periphery of the drive ring 20. The gear portion 25 is composed of a gear tooth portion that extends in an arc shape in the circumferential direction and has a plurality of gear teeth formed on its outer periphery, and a portion that extends radially outward from the blade support portion 31 and is connected to the gear tooth portion.

[0024] Further, a radial support portion (rotation support portion) 26 extending toward the presser plate 40 in the thrust direction is formed on the circumferential direction of the surface of the drive ring 20 opposite the blade support portion 31. The radial support portion 26 of the drive ring 20 fits into the inner peripheral portion of the presser plate 40 and is supported rotatably around the central axis 5.

[0025] Furthermore, thrust pressing protrusions 29 are provided on the front and back of the drive ring 20 at multiple locations (11 locations in this embodiment) in the circumferential direction near the outer periphery on the pressing plate side. The sheet member 30 rests on the thrust pressing protrusions 52 of the base plate 50, and the thrust pressing protrusions 29 of the drive ring 20 are sandwiched between the pressing plate 40, so that the drive ring 20 is rotatably supported in the thrust direction by the pressing plate 40.

[0026] Further, a light-shielding protrusion 28 is provided at one location in the circumferential direction of the drive ring 20, which is inserted between the light-emitting portion and the light-receiving portion of the photointerrupter 3 to provide light shielding.

[0027] As shown in FIG. 1, the retaining plate 40 is formed in a ring shape with a light passage opening 44 in its center, and is positioned so as to cover (hold down) the diaphragm blades 10 and drive ring 20 arranged between the retaining plate 40 and the base plate 50, and is fixed to the base plate 50 with five screws 60.

[0028] The base plate 50 is formed in a ring shape with a light passage opening 54 as a fixed opening in its center, and the ring-shaped portion is formed with multiple cam groove portions (11 as many as the aperture blades 10) into which the cam pins 12 of the multiple aperture blades 10 respectively engage.

[0029] Furthermore, a sheet member 30 is provided on the blade surface side of the base plate 50 and on the blade surface side of the drive ring 20 so that the drive ring can be made smaller.

[0030] In this embodiment, "supporting (or holding)" the diaphragm blade 10 means providing the necessary play for smooth rotation of the diaphragm blade 10 while restricting the movement so that the diaphragm blade 10 does not rattle or fall off any further. In other words, it does not mean holding the diaphragm blade 10 so that there is no play in any direction other than the rotation direction (thrust direction).

[0031] In the light amount adjusting device configured as described above, when the actuator 1 operates to rotate the pinion gear 2, the drive ring 20 rotates around the central axis 5 (in the circumferential direction) relative to the base plate 50 and the presser plate 40. The drive ring 20 transmits the driving force from the actuator 1 to the eleven diaphragm blades 10 via the drive pins 11. As a result, the cam pins 12 move along the cam groove portions 51, causing each diaphragm blade 10 to rotate around the drive pins 11.

[0032] The rotational position of the drive ring 20 is controlled by the actuator 1, thereby controlling the rotational position of the plurality of diaphragm blades 10, that is, the size (diameter) of the diaphragm aperture (variable aperture) formed by the blade portions of the plurality of diaphragm blades 10. The amount of light passing through the light passage openings 44, 24, 54 can be changed (adjusted) depending on the diaphragm aperture diameter.

[0033] The initial rotational position of the drive ring 20, which is necessary to control the rotational position of the drive ring 20, can be detected by detecting a signal indicating that the light-shielding protrusion 28 of the drive ring 20 has entered between the light-emitting and light-receiving parts of the photointerrupter 3 and blocked the light from the light-emitting part.

[0034] Here, the problems with conventional light amount adjusting devices will be explained. In the light amount adjusting device of Patent Document 1, the blade surface of the diaphragm blade on the side of the presser plate is supported by a drive ring and a sheet member.

[0035] The blade support portion provided by the drive ring has a flat, uniform surface, except for the hole shapes where the drive pins of the diaphragm blades engage with the drive holes of the drive ring, and a radial support portion that runs all the way around is provided on the surface of the drive ring opposite the blade support portion, and the inner circumferential side of the radial support portion has a plurality of rib shapes around and between the plurality of drive holes where the drive pins of the diaphragm blades respectively engage.

[0036] Furthermore, a plurality of recesses are provided in addition to the plurality of rib shapes on the inner circumferential side of the radial support portion of the drive ring in the circumferential direction, and since they are not hole-shaped, the drive ring is heavy.

[0037] In the light amount adjusting device of Patent Document 2, the blade surface of the diaphragm blade on the side of the presser plate is supported by a drive ring and a blade support portion of the presser plate.

[0038] The blade support portion of the drive ring has multiple holes passing through it, and the surface opposite the blade support portion has three radial support portions in the circumferential direction. Since the entire circumference is not connected, the strength is weakened and the ring deforms during operation, resulting in unstable operation.

[0039] The drive ring also has a plurality of rib shapes around and between a plurality of drive holes in which the drive pins of the diaphragm blades are engaged, on the inner circumferential side of the radial support portion.

[0040] On the other hand, in the light amount adjusting device of this embodiment, the blade surface of the diaphragm blade 10 on the side of the presser plate is supported by the drive ring 20 and the sheet member 30 as shown in FIG.

[0041] As shown in FIG. 4, the blade support portion 31 of the drive ring 20 is provided with a plurality of holes passing therethrough, through which the drive pins 11 of the plurality of diaphragm blades 10 engage with the drive holes 23 of the drive ring 20 .

[0042] In addition, a radial support portion 26 that is connected all the way around in the circumferential direction is provided on the surface opposite the blade support portion 31 of the drive ring 20, which makes it possible to maintain high strength, reduces the risk of deformation during operation, and enables stable operation.

[0043] As shown in FIG. 3, the hole shape 21 of the drive ring 20 is located on the inner circumferential side of the radial support portion 26, the hole shape 21 is a through hole, and is covered by the aperture blades 10 to prevent light leakage and reflection in all usage states, from the fully opened state in FIG. 5 to the small aperture state in FIG. 6.

[0044] Furthermore, as shown in FIG. 3, the radial support portion 26 has a plurality of rib shapes 22 around the inner circumferential side thereof and between the drive holes 23 into which the drive pins 11 of the diaphragm blades 10 are respectively engaged.

[0045] The blade support portion 31 of the drive ring 20 has the same number of gate shapes 27 as the number of drive holes 23, and these are arranged evenly in the circumferential direction.

[0046] Furthermore, a plurality of hole shapes 21a, 21b are provided symmetrically and evenly in the circumferential direction on the inner periphery side of the radial support portion 26 relative to the gate shape 27, and all of the hole shapes 21 have the same shape.

[0047] Furthermore, the drive holes 23 of the drive ring 20 are equally spaced between each of the gate shapes 27 and are all the same distance from the gate 27 .

[0048] The gate shapes 27 are evenly arranged with respect to the plurality of hole shapes 21a and 21b, When resin flows into and forms the drive hole 23 of the drive ring 20, the resin flowing out from the left and right gate shapes 27 reaches the drive hole 23 at the same time, so that the resin is filled uniformly and in a balanced manner with the same pressure, enabling the drive hole 23 to be molded with good dimensional accuracy.

[0049] The drive hole 23 is formed with good dimensional accuracy, so that the drive pins 11 of the diaphragm blades 10 are engaged with each other, and when the diaphragm blades 10 are stopped down, a stably aligned diaphragm shape can be formed, and the side length ratio and circularity can be improved.

[0050] Further, the blade surfaces of the drive ring 20 of the diaphragm blade 10 are supported by the blade support part 31 of the drive ring, and the diaphragm blade 10 operates to move in and out without getting caught in the plurality of hole shapes 21 provided in the blade support part 31.

[0051] This allows the weight of the drive ring 20 to be reduced, and the contact area between the diaphragm blades 10 and the drive ring 20 to be reduced. As a result, the inertia of the drive ring 20 and the frictional resistance that the diaphragm blades 10 receive from the drive ring 20 can be reduced, allowing the diaphragm blades 10 to rotate smoothly.

[0052] Furthermore, as shown in Figure 9, conventional drive rings are made of glass fiber and contain fillers, which results in a high fiber orientation in the parallel direction (circumferential direction), which can result in different molding shrinkage rates in the perpendicular direction (radial direction) and the parallel direction.

[0053] If the molding shrinkage rate differs between the perpendicular and parallel directions, when the molten resin solidifies as it cools during molding, its volume decreases, and the molded product shrinks. This difference in shrinkage between the perpendicular and parallel directions can cause warping.

[0054] On the other hand, as shown in FIG. 10, the drive ring 20 of this embodiment uses a low-warpage material and is formed from glass flake material, and therefore, although it contains filler, the fiber orientation is low.

[0055] Therefore, since the fibers have no regularity in the vertical and parallel directions and are characterized by a complex intersecting pattern, the molding shrinkage rate is uniform in the vertical and parallel directions, and when the molded product shrinks during molding, it does not change in the vertical and parallel directions, making it less likely to warp and enabling stable molding.

[0056] Furthermore, as shown in Figure 11, when glass bead material is used, the fiber orientation is low, just like with glass flake material, and the molding shrinkage rate does not change between the perpendicular and parallel directions during molding, allowing for stable molding.

[0057] (Other Examples) FIG. 12 shows an interchangeable lens 221 for a single-lens reflex camera, which is an imaging device equipped with the diaphragm device described in the first embodiment, and the internal configuration of the camera body to which the interchangeable lens is attached.

[0058] The lens barrel of the interchangeable lens 221 houses a photographic optical system including a variable magnification lens 232, the diaphragm device 100 of the first embodiment that narrows the optical path, and a focus lens 229.

[0059] The image sensor 225, which is composed of a photoelectric conversion element such as a CCD sensor or a CMOS sensor, is disposed inside the camera body and photoelectrically converts the subject image formed by the interchangeable lens 221 to output an electrical signal. The brightness of the subject image formed on the image sensor 225 (i.e., the amount of light reaching the image sensor 225) can be appropriately set by changing the diaphragm opening of the diaphragm device 100 or by moving an ND filter (not shown) forward or backward.

[0060] The electrical signal output from the image sensor 225 is converted into a digital signal in the image processing circuit 226 and subjected to various image processing, thereby generating an image signal.

[0061] A user can change the magnification (zoom) by moving a variable magnification lens 232 by rotating a zoom ring 231. The controller 222 detects the contrast of an image signal, controls a focus motor 228 in accordance with the contrast, and moves a focus lens 229 to perform autofocus. Alternatively, the controller 222 may control the focus motor 228 and move a focus lens 229 to perform autofocus based on a detection signal from a focus detection means that uses a phase difference detection method (not shown).

[0062] Furthermore, the controller 222 controls the driver 5a of the diaphragm device 100 to adjust the amount of light based on the photometric value of a photometric means (not shown) or an image signal. This makes it possible to make blur and ghosting during photography natural, and to record high-quality images.

[0063] The present invention is not limited to the single-lens reflex camera described above, but can also be widely applied to optical devices such as digital cameras with an integrated lens, video cameras, and the like. [Explanation of symbols]

[0064] 1 actuator 2 pinion gears 3 Photointerrupter 10 aperture blades 20 Drive ring 30 Sheet material 40 Retaining plate 50 Main plate

Claims

1. a base member having a fixed opening through which light passes; a plurality of diaphragm blades arranged in a circumferential direction of the fixed opening to form a variable opening through which the light passes; a light amount adjusting device having a drive ring that rotates in a circumferential direction of the fixed aperture to transmit a driving force to the aperture blades, thereby rotating the plurality of aperture blades so as to change the size of the variable aperture, A light amount adjusting device, characterized in that the blade support portion of the drive ring has a hole shape, and the radial support portion of the drive ring is connected all around.

2. The light amount adjusting device according to claim 1 , The light amount adjusting device is characterized in that the drive ring has a plurality of gate shapes arranged at equal intervals in the circumferential direction, and has hole shapes corresponding to the gate shapes, which are arranged symmetrically and evenly.

3. The light amount adjusting device according to claim 1 , A light intensity adjusting device characterized in that the blade surface on the drive ring side is supported by the drive ring, and the blade support portion is penetrated by a plurality of hole shapes provided in addition to the drive hole portion into which the drive pin engages.

4. The light amount adjusting device according to claim 1 , The light amount adjusting device is characterized in that the plurality of holes formed in the drive ring are formed on the inner circumferential side of the radial support portion.

5. The light amount adjusting device according to claim 1 , A light amount adjusting device, characterized in that the plurality of holes formed in the drive ring are covered by the diaphragm blades in all use states from the open state to the small aperture state.

6. The light amount adjusting device according to claim 1 , The light amount adjusting device is characterized in that the drive ring is made of a low-warpage material having the same molding shrinkage rate in the vertical and horizontal directions for the purpose of stable molding.

7. 7. An optical device comprising: the light amount adjusting device according to claim 1; and an imaging element that captures an image of light that has passed through the light amount adjusting device.

Images