Blade driving device, and optical instrument

Abstract

To provide a blade driving device that does not impair assemblability in assembly of a first stationary member (cam plate), diaphragm blades, and a rotation member (driving ring).SOLUTION: A blade driving device comprises: a plurality of diaphragm blades 106 that come in and out of a light passage path; a driving ring 103 that is provided with an engagement part for engagement to drive the diaphragm blades 106; and a cam plate 107 that has cam grooves 107b and blade contact parts 107f. The diaphragm blades 106 each have a cam pin 106b that is inserted into the cam groove 107b, and a part to be engaged that is engaged with the engagement part. With the cam pin 106b in contact with one end of the cam groove 107b, and the diaphragm blade 106 and the blade contact part in contact with each other, the part to be engaged and the engagement part are arranged on the same circumference.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a blade drive device in which diaphragm blades are driven by a rotating member that rotates using a motor as a drive source, and to an optical apparatus equipped with the same. [Background technology]

[0002] Conventionally, blade drive devices using a stepping motor, such as diaphragm devices used in optical equipment, comprise an aperture unit in which an annular rotating member (drive ring) and diaphragm blades are sandwiched between two fixed members. The diaphragm blades are fitted with dowels that fit into holes in the drive ring and multiple cams cut into the first fixed member (cam plate). The diaphragm blades are driven by the sliding of the dowels along the cams as the drive ring rotates, thereby blocking the opening holes in the cam plate and drive ring and enabling the blades to be driven to the set aperture value.

[0003] Now, when considering the assembly procedure for fitting the drive ring and the aperture blades in the aperture unit configured as described above, the aperture blades are first assembled by engaging one of the dowels of the aperture blade with the cam groove on the cam plate, and then the drive ring is assembled by engaging the hole in the drive ring with the other dowel of the aperture blade. When assembling the drive ring, it is necessary to lower the multiple aperture blades from above so that the dowels of the aperture blades and the multiple holes in the drive ring are inserted at once. Therefore, it is necessary to align the rotational positions of the multiple aperture blades in advance so that the dowels of the aperture blades and the multiple holes in the drive ring have the same diameter, which makes the structure extremely difficult to assemble. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-20359 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to solve such problems, the present invention provides a blade drive device that does not impair the ease of assembly when assembling a first fixed member (cam plate), aperture blades, and a rotating member (drive ring). [Means for solving the problem]

[0006] In order to solve the above problem, the blade drive device of the present invention includes: a plurality of diaphragm blades that move in and out of a light passage; a drive ring provided with engagement portions that engage with the diaphragm blades to drive them; and a cam plate having a cam groove and a blade abutment portion, wherein the diaphragm blade has a cam pin that is inserted into the cam groove and an engaged portion that engages with the engaging portion, and when the cam pin is abutted against one end of the cam groove and the diaphragm blade and the blade abutment portion are abutted against each other, the engaged portion and the engaging portion are arranged on the same circumference. [Effects of the Invention]

[0007] According to the present invention, the ease of assembly of the first fixed member (cam plate), diaphragm blades, and rotating member (drive ring) can be prevented from being impaired. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an exploded perspective view of a blade drive device according to an embodiment; [Figure 2] Perspective view of the drive unit [Figure 3] A perspective view of a support member [Figure 4] Perspective view of the drive ring [Figure 5] A perspective view of a partition member [Figure 6] Perspective view of aperture blades [Figure 7] Perspective view of the cam plate [Figure 8] FIG. 2 is a cross-sectional view of the blade drive device according to the embodiment. [Figure 9] Plan view of the aperture blades in contact with the cam plate [Figure 10] 1 is a schematic diagram of an imaging apparatus equipped with an aperture device according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0010] 1 shows an exploded perspective view of a diaphragm device 100 as a light amount adjustment device, which is an example of a blade drive device according to an embodiment of the present invention. The diaphragm device of the present invention is mounted in an imaging device such as a camera, and is used as a light amount adjustment device that adjusts the amount of light that reaches an imaging element.

[0011] As shown in Fig. 1, the aperture stop device 100 according to this embodiment has a support member 102 with an opening formed in the center. The support member 102 is made by resin molding, but is not limited to this. A drive unit 101 is attached to the support member 102 with screws 108.

[0012] 2 is a perspective view of the drive unit 101. The drive unit 101 is composed of a stepping motor 101a and a mounting plate 101b. The mounting plate 101b has a screw fastening portion 101c, and is attached to the support member 102 via the screw fastening portion 101c with a screw 108. In addition, a pinion 104 is attached to the rotation shaft 101d of the drive unit 101.

[0013] 3 is a perspective view of the support member 102. (A) is a view of one side, and (B) is a view of the opposite side. The support member 102 is provided with a screw hole portion 102b into which a screw 108 is screwed, and a motor-facing portion 102c. In the aperture device 100, the stepping motor 101a is mounted on one side of the support member 102 so as to face the motor-facing portion 102c.

[0014] The diaphragm device 100 also has a drive ring 103, which is a rotating member that rotates around the opening on the other side of the support member 102. FIG. 4 is a perspective view of the drive ring 103. The drive ring 103 is sandwiched between multiple protrusions 107e of a cam plate 107 (described later) and multiple protrusions 102a of the support member 102. The drive ring 103 is made by resin molding, but is not limited to this. A gear portion 103c of the drive ring 103 engages with the pinion 104, enabling transmission of driving force. The drive ring 103 is provided with a drive hole 103b, into which a drive pin 106a, which is an engagement shaft of the diaphragm blade 106, a blade member, is engaged. In other words, the drive ring 103 is configured to move the diaphragm blade 106 in and out of the light passage path as the drive ring 103 rotates, and therefore serves as a member (power transmission member) for driving the diaphragm blade 106.

[0015] Furthermore, it is preferable that one or both surfaces of the base 103a of the drive ring 103 are surface-treated. Examples of surface treatments include, for example, sliding coating, antistatic treatment, and antireflection treatment. The sliding coating reduces friction between the drive ring 103 and the sliding parts, that is, the support member 102 and the cam plate 107, enabling operation with less power. The antireflection treatment also reduces reflection of light that enters the light amount adjustment device, preventing the occurrence of ghosts, flares, and the like when the light amount adjustment device is incorporated into a lens barrel.

[0016] FIG. 5 is a perspective view of partition member 105. Partition member 105 has an opening in the center. Partition member 105 is defined in the radial direction relative to cam plate 107 by engaging engagement portions 107d of cam plate 107 (described later) with engagement holes 105a of partition member 105, and defined in the optical axis direction by being sandwiched between multiple protrusions 107a of cam plate 107 and support member 102. In FIG. 7, some of protrusions 107a are indicated by reference numerals. Partition member 105 can press the positions of cam pins 106b of blades 106 from the opposite side of cam pins 106b, thereby preventing cam pins 106b inserted into cam grooves 107b of aperture forming member 107 (described later) from falling out of cam grooves 107b.

[0017] The partition member 105 is made by pressing a resin film, but may also be made by resin molding.

[0018] FIG. 6 is a perspective view of diaphragm blade 106. (A) is a view of one side, and (B) is a view of the opposite side. Drive pin 106a and cam pin 106b, which are engaged with engagement holes in drive ring 103, are provided on blade portion 106h. Diaphragm blade 106 is formed by pressing a PET sheet material to form blade portion 106h, and drive pin 106a and cam pin 106b are formed and attached by resin molding. However, for example, blade portion 106h, drive pin 106a, and cam pin 106b may be formed integrally by resin molding. Blade portion 106h has an aperture-forming portion, and the edge on the opposite side thereof is called outer edge portion 106c.

[0019] Furthermore, although this embodiment is configured with nine diaphragm blades, the number of diaphragm blades may be any number equal to or greater than two. While this embodiment will be described using diaphragm blade 106 as an example, various blade drive devices may be used, such as other shutter blades or blades with optical filters. The maximum opening through which light passes may be determined by the opening of cam plate 107 or support member 102, or may be determined by the ends of the multiple diaphragm blades 106.

[0020] Alternatively, blade portion 106h may be made from a sheet material that has been subjected to a surface treatment such as a light-blocking treatment by pressing a PET sheet material or the like, and drive pin 106a and cam pin 106b may be made by resin molding and integrated with blade portion 106h by bonding, welding, outsert molding, etc. Alternatively, drive pin 106a and cam pin 106b may be made from metal pins and integrated with blade portion 106h by bonding, welding, caulking, etc.

[0021] FIG. 7 is a perspective view of the cam plate 107. The cam plate 107 has protrusions 107a, which serve as multiple support portions for supporting the partition member 105, multiple cam grooves 107b, and multiple protrusions 107e, which serve as multiple support portions for supporting the drive ring 103. Furthermore, a blade contact portion 107f is formed on the protrusion 107a. Positioning the protrusions 107a between two adjacent cam grooves facilitates the radial miniaturization of the aperture. Furthermore, it is desirable to position the protrusions 107a and the blade contact portion 107f away from the cam grooves to minimize variation in the position of the diaphragm blades 106 during assembly. In FIG. 7, only some of these portions are indicated by reference numerals. In the optical axis direction, the drive ring 103 drives within the space formed between the support member 102 and the partition member 105, and the diaphragm blades 106 drive within the space formed between the partition member 105 and the cam plate 107.

[0022] The drive pin 106a of the diaphragm blade 106 engages with the drive hole 103b of the drive ring 103. When the pinion 104 rotates and a driving force is transmitted to the gear portion 103c of the drive ring 103, the drive ring 103 rotates. When the drive ring 103 rotates, a driving force is applied from the drive hole 103b of the drive ring 103 to the drive pin 106a of the diaphragm blade 106, driving the diaphragm blade 106. The cam pin 106b of the diaphragm blade 106 engages with a cam groove 107b formed in the cam plate 107. Guided by the cam groove 107b, the diaphragm blade 106 moves in and out of the opening in the support member 102. The multiple diaphragm blades 106 adjust the diaphragm shape, making it possible to adjust the amount of light passing through.

[0023] Next, support of the diaphragm blades 106 by the drive ring 103 will be described. The multiple diaphragm blades 106 are uniformly arranged in the circumferential direction. In this embodiment, the rotation of the drive ring 103 moves the multiple diaphragm blades 106 in conjunction with each other, making it possible to change the size of the light passing aperture.

[0024] Next, setting of the thrust position (position in the optical axis direction) of the screw fastening portion 101c in this embodiment will be described. Fig. 8 is a cross-sectional view of the blade drive device of this embodiment, and the thrust position is set so that the screw fastening portion 101c is located between the motor-facing portion 102c of the support member 102 and the gear portion 103c of the drive ring 103. In other words, the screw fastening portion 101c is recessed into the support member 102. By moving the thrust direction position of the screw fastening portion 101c closer to the support member 102 in this way, the screw 108 can also be moved closer to the support member 102, thereby reducing the space in the thrust direction.

[0025] Next, the assembly procedure of this embodiment will be described. As shown in Fig. 1, the diaphragm device 100 of this embodiment is composed of nine diaphragm blades 106. However, since all of the diaphragm blades 106 have a symmetrical structure with respect to the center of the diaphragm opening, the following description will only cover some of the diaphragm blades 106, but the same applies to the other diaphragm blades 106.

[0026] First, in the assembly procedure, a plurality of diaphragm blades 106 are mounted on cam plate 107 so that cam pins 106b on the backside engage with cam grooves 107b of cam plate 107. At this time, cam groove end 107c, which is one end of cam groove 107b, is brought into contact with cam pin 106b, and blade contact portion 107f on cam plate 107 is brought into contact with outer edge 106c of diaphragm blade 106. A plan view of this state is shown in Figure 9. Next, partition member 105 is mounted on cam plate 107 so as to sandwich diaphragm blade 106 therebetween.

[0027] Thereafter, the drive ring 103 is assembled so that the drive holes 103b of the drive ring 103 and the drive pins 106a of the diaphragm blades 106 fit together. Note that, because the drive holes 103b of the drive ring 103 and the drive pins 106a of the diaphragm blades 106 are on the same circumference, it becomes easy to fit a plurality of drive holes 103b into the drive pins 106a.

[0028] Thereafter, the support member 102 to which the drive unit 101 has been attached in advance is assembled onto the cam plate 107 so as to sandwich the diaphragm blades 106 and the partition member 105 therebetween.

[0029] Furthermore, in this embodiment, during the above-described assembly procedure, blade abutment portions 107f are provided on protrusions 107a, which serve as multiple support portions that support outer edge portions 106c of diaphragm blades 106 and partition member 105, but blade abutment portions 107f for abutting against outer edge portions 106c may be separately provided on cam plate 107.

[0030] In this embodiment, the partition member 105 is provided at a position where it is sandwiched between the plurality of protrusions 107a of the cam plate 107 and the support member 102, but the partition member 105 may be omitted.

[0031] (Other Examples) FIG. 10 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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).

[0036] Furthermore, the controller 222 controls the driver 5 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.

[0037] 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.

[0038] For example, a blade drive device and an optical device equipped with a blade drive device that includes a plurality of diaphragm blades 106 that move in and out of a light passageway, a drive ring 103 having a gear portion 103c that drives the diaphragm blades 106, a motor 101a equipped with a pinion 104 that meshes with the gear portion 103c, a support member 102 that supports the motor 101a and the diaphragm blades 106, and a mounting plate 101b that is fixed to the motor 101a and has formed thereon screw fastening portions 101c that are fastened to the support member 102 with screws, the screw fastening portions 101c being disposed between one side of the support member 102 that is the mounting side of the motor 101a in the optical axis direction and the gear portion 103c can be made thinner without impairing ease of assembly. [Explanation of symbols]

[0039] 101 Drive unit 101a stepping motor 101b Mounting plate 101c Screw fastening part 102 Support member 102b screw hole 102c Motor facing part 103 Drive ring 103b Drive hole 103c Gear section 104 Pinion 105 Partition material 106 aperture blades 106a Drive pin 106b Campin 106c outer edge 107 Cam plate 107a Protrusion 107b Cam groove 107c Cam groove end 107f Blade contact part 108 Bis

Claims

1. a plurality of aperture blades that move in and out of a light passageway; a drive ring provided with an engagement portion that engages with the diaphragm blades to drive the diaphragm blades; a cam plate having a cam groove and a blade abutment portion, the diaphragm blade has a cam pin inserted into the cam groove and an engaged portion engaged with the engaging portion, When the cam pin is brought into contact with one end of the cam groove and the diaphragm blade is brought into contact with the blade contact portion, the engaged portion and the engaging portion are arranged on the same circumference. A blade drive device characterized by the above.

2. An optical device comprising an imaging element for imaging light that has passed through the blade drive device according to claim 1.

Images