Blade drive device and optical instrument

Abstract

To provide a blade drive device and optical instrument that can improve aperture accuracy while reducing the load on the drive unit. [Solution] To solve the above problems, the light-transmitting blade drive device of the present invention comprises an opening-forming member 102 having an opening, a plurality of blade members 107 that move in and out of the opening of the opening-forming member 102, a drive ring 105 that provides driving force to the plurality of blade members 107, and a plurality of biasing members 106 that bias each of the plurality of blade members 107 with respect to the drive ring 105, wherein the plurality of biasing members 106 are a plurality of torsion springs, and one arm portion 106a is locked to a locking portion provided on the drive ring 105.

Description

Technical Field

[0001] The present invention relates to a blade driving device in which a diaphragm blade is driven by a rotating member that rotates with a motor as a driving unit, and an optical device including the same.

Background Art

[0002] Conventionally, for example, Patent Document 1 is known as a technique in such a field. In the diaphragm device described in this Patent Document 1, the output of a stepping motor is transmitted from an output gear provided on an output shaft to a driving ring via a parent and child gear, and a plurality of diaphragm blades interlocked with the driving ring are relatively moved to set an arbitrary diaphragm opening diameter.

[0003] Further, the diaphragm blades are biased in the maximum diaphragm opening direction by a torsion coil spring. This eliminates mechanical play between each diaphragm blade and the driving ring, achieving an improvement in diaphragm accuracy.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the diaphragm device described in Patent Document 1, in addition to the load for driving the driving ring and each diaphragm blade, a load due to the torsion coil spring is generated, so that the load on the stepping motor as the driving unit also increases. In particular, the load due to the torsion coil spring becomes maximum at the minimum diaphragm opening, and when trying to set the output of the stepping motor for that load, it leads to an increase in the size of the stepping motor and an increase in power consumption.

[0006] The present invention was made to solve these problems and aims to provide a blade drive device and optical instrument that can reduce the load on the drive unit while achieving improved aperture accuracy. [Means for solving the problem]

[0007] To solve the above problems, the blade drive device of the present invention comprises an opening forming member having an opening that allows light to pass through, a plurality of blade members that move in and out of the opening of the opening forming member, a drive ring that provides driving force to the plurality of blade members, and a plurality of biasing members that bias each of the plurality of blade members with respect to the drive ring, wherein the plurality of biasing members are a plurality of torsion springs, and one arm of each spring is locked to a locking portion provided on the drive ring. [Effects of the Invention]

[0008] According to the present invention, it is possible to improve aperture accuracy while reducing the load on the drive unit. [Brief explanation of the drawing]

[0009] [Figure 1] Exploded perspective view of the blade drive device according to the embodiment. [Figure 2] Perspective view of the opening forming member [Figure 3] Perspective view of the drive ring [Figure 4] Perspective view of aperture blades [Figure 5] Perspective view of the cover component [Figure 6] Perspective view of a torsion coil spring [Figure 7] Cross-sectional view of the torsion coil spring assembly in the optical axis direction. [Figure 8] A plan view of the main part showing the control state of the maximum aperture of the blade drive device according to the embodiment. [Figure 9] A plan view of the main part showing the control state of the minimum aperture of the blade drive device according to the embodiment. [Figure 10] A diagram showing the torque generated by the torsion coil spring in the embodiment. [Figure 11] Schematic diagram of an imaging device equipped with an aperture device according to the first embodiment. [Modes for carrying out the invention]

[0010] (First embodiment) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] Figure 1 shows an exploded perspective view of an aperture device 100, which is an example of a blade drive device according to an embodiment of the present invention, and serves as a light intensity control device. The aperture device of the present invention is mounted on an imaging device such as a camera and is used as a light intensity control device to adjust the amount of light reaching the image sensor.

[0012] As shown in Figure 1, the throttling device 100 according to this embodiment has an opening-forming member 102 with an opening formed in the center. Figure 2 is a perspective view of the opening-forming member 102. Nine mounting shafts 102b are erected on one surface of the opening-forming member 102 at approximately equal angular intervals around the opening. The opening-forming member 102 is made by resin molding, but is not limited to this. A drive unit 101 is attached to the opening-forming member 102. The drive unit 101 can be, for example, a stepping motor or a galvanometer motor. A pinion 103 is attached to the rotating shaft 101a of the drive unit 101. The pinion 103 meshes with the large gear of a two-stage gear 104 arranged on the opening-forming member 102, and the small gear of the two-stage gear 104 meshes with the gear portion 105c of a drive ring 105, which will be described later.

[0013] In addition, the aperture device 100 has a drive ring 105 which is a rotating member that rotates around the periphery of the aperture on one surface of the aperture forming member 102. FIG. 3 is a perspective view of the drive ring 105. The drive ring 105 is sandwiched by a protrusion 108a of a cover member 108 and a plurality of protrusions 102a of the aperture forming member 102, which will be described later. The drive ring 105 is made by resin molding, but is not limited thereto. The gear portion 105c of the drive ring 105 is meshed with the pinion 103 via the two-stage gear 104 so that the driving force can be transmitted. A cam groove 105b is provided in the drive ring 105, and a cam pin 107b, which is an engagement shaft of the aperture blade 107 that is a blade member, engages with the cam groove 105b. That is, since the drive ring 105 is configured to be interlocked so that the aperture blade 107 enters and exits with respect to the light passing path as the drive ring 105 rotates, the drive ring 105 serves as a member (power transmission member) for driving the aperture blade 107. Further, a locking portion 105d of a torsion coil spring 106, which will be described later, is erected on the drive ring 105. The locking portion 105d is set so as to overlap in the optical axis direction with a groove portion 102c provided in the aperture forming member 102.

[0014] Also, it is preferable that the base portion 105a of the drive ring 105 is surface-treated on one side or both sides. As an example of the surface treatment, for example, there are sliding painting, antistatic treatment, antireflection treatment, and the like. By performing sliding painting, the friction between the drive ring 105 and the aperture forming member 102 and the cover member 108, which are parts that slide with the drive ring 105, can be reduced, and operation with power saving becomes possible. Further, by performing antireflection treatment, the reflection of the light that has entered the optical amount adjustment device can be suppressed, and the occurrence of ghost, flare, etc. when the optical amount adjustment device is incorporated in the lens barrel can be prevented.

[0015] FIG. 4 is a perspective view of the aperture blade 107. A cam pin 107b, which is an engaged portion between the mounting hole 107a for rotatably mounting on the mounting shaft 102b of the aperture forming member 102 and the cam groove 105b of the drive ring 105, is provided on the blade portion 107h. The aperture blade 107 is formed by pressing a PET sheet material to form the blade portion 107h, and the cam pin 107b is formed and attached by resin molding. For example, the blade portion 107h and the cam pin 107b may be integrally formed by resin molding. The blade portion 107h has an aperture forming portion, and the edge on the opposite side is the outer edge portion 107c.

[0016] In addition, in this embodiment, the aperture blades are composed of nine aperture blades, but the number of aperture blades may be any number as long as it is two or more. The maximum aperture of the portion where light passes may be defined by the aperture of the cover member 108 or the aperture forming member 102, or may be defined by the ends of the plurality of aperture blades 107.

[0017] Also, the blade portion 107h may be formed by pressing a PET sheet material or the like and using a sheet member that has been surface-treated such as a light-shielding treatment. The cam pin 107b is formed by resin molding and integrated with the blade portion 107h by adhesion, welding, outsert molding, or the like. Further, the cam pin 107b may be formed of a metal pin and integrated with the blade portion 107h by adhesion, welding, caulking, or the like. In the optical axis direction, the drive ring 105 and the aperture blade 107 drive through the space formed by being sandwiched between the aperture forming member 102 and the cover member

[0018] 108.

[0018] The cam pin 107b of the aperture blade 107 engages with the cam groove 105b of the drive ring 105. When the pinion 103 rotates and a driving force is transmitted to the gear portion 105c of the drive ring 105 via the double gear 104, the drive ring 105 rotates. When the drive ring 105 rotates, a driving force is applied from the cam groove 105b of the drive ring 105 to the cam pin 107b of the aperture blade 107, and guided by the cam groove 105b, the aperture blade 107 enters and exits the inside and outside of the aperture of the cover member 108. The aperture shape is adjusted by the plurality of aperture blades 107, and the amount of light passing through can be adjusted.

[0019] Figure 5 is a perspective view of the cover member 108. The cover member 108 has a projection 108a that serves as a support for the drive ring 105, a groove 108b, and an opening 108c that serves as a diaphragm device 100.

[0020] Figure 6 is a perspective view of the torsion coil spring 106. The torsion coil spring 106, acting as a biasing member, consists of two arms 106a and 106b and a coil portion 106c. The coil portion 106c of the torsion coil spring 106 is wound around the mounting shaft 102b of the opening forming member 102. One arm 106a of the torsion coil spring 106 is hooked onto the locking portion 105d of the drive ring 105, and in the optical axis direction, it is positioned in the space between the drive ring 105 and the cover opening forming member 102 to prevent it from coming loose. The other arm 106b is bent in the optical axis direction and hooked onto the outer edge portion 107c of the aperture blade 107, biasing the aperture blade 107 toward the minimum aperture opening. As a result, the cam pin 107b of the aperture blade 107 is constantly pressed against the cam groove 105b of the drive ring 105. Furthermore, the arm portion 106b is set to overlap with the groove portion 108b of the cover member 108 in the optical axis direction. This prevents the arm portion 106b from detaching from the outer edge portion 107c of the aperture blade 107 even if the blade drive mechanism is subjected to shock or other impacts. Figure 7 is a cross-sectional view of the torsion coil spring assembly portion in the optical axis direction.

[0021] Next, the operation of this embodiment will be described. Figure 8 shows an enlarged view of the state in which the nine aperture blades 107 are open wider than the opening 108c of the cover member 108, that is, the state of maximum aperture control. At this time, each aperture blade 107 is constantly biased in the direction of minimum aperture opening by each torsion coil spring 106, so there is no play between the aperture blades 107 and the cam groove 105b of the drive ring 105, and this state is preferably maintained. If the subject light is darker than a predetermined brightness, the shooting is carried out as is, but if the subject light is brighter than a predetermined brightness, the pinion 103 attached to the drive unit 101 is rotated clockwise. As a result, the drive ring 105 is rotated clockwise via the two-stage gear 104, and the nine aperture blades 107, biased by the torsion coil spring 106, are pressed against the cam groove 105b of the drive ring 105 and simultaneously rotated counterclockwise, entering the opening 108c of the cover member 108, and the aperture opening is reduced by the cooperation of each aperture blade 107. Figure 9 shows the state in which the nine aperture blades 107 have reached the minimum aperture opening position.

[0022] Furthermore, when the aperture blades 107 have entered the opening 108c of the cover member 108, if the subject light is darker than a predetermined brightness, the pinion 103 attached to the drive unit 101 is rotated counterclockwise. As a result, the drive ring 105 is rotated counterclockwise via the two-stage gear 104, so that the nine aperture blades 107, biased by the torsion coil spring 106, are pressed against the cam groove 105b of the drive ring 105 against the biasing force of the torsion coil spring 106, and at the same time rotated clockwise, retracting from the opening 108c of the cover member 108, and the aperture opening is enlarged through the cooperation of each aperture blade 107. At this time, since it is necessary to operate the drive ring 105 against the biasing force of the torsion coil spring 106, the biasing force of the torsion coil spring 106 becomes a load on the drive unit 101.

[0023] Next, the torque generated by the torsion coil spring 106 during the above operation will be explained. During operation, the arm portion 106a that is attached to the locking portion 105d of the drive ring 105 and the arm portion 106b that is attached to the outer edge portion 107c of the aperture blade 107 rotate by approximately the same angle. That is, the torque generated by the torsion coil spring 106 during operation is approximately constant. Figure 10 shows the change in the torque generated by the torsion coil spring 106 with respect to the rotation angle of the aperture blade 107 in this embodiment, and the change in the torque generated when one of the arms is not movable (conventional example). In this embodiment, the peak of the torque generated by the torsion coil spring 106 due to the rotation of the drive ring 105 and the aperture blade 107 is reduced. That is, the load on the drive unit 101 can be reduced.

[0024] In this embodiment, since the aperture blades 107 are always biased in the direction of the minimum aperture opening, there is no play between the aperture blades 107 and the drive ring 105, allowing any desired aperture diameter to be obtained appropriately, and reducing the load on the drive unit 101 due to the biasing force of the torsion coil spring 106.

[0025] (Second Embodiment) Figure 11 shows the internal configuration of an interchangeable lens 221 for a single-lens reflex camera, which is an imaging device equipped with the aperture device described in the first embodiment, and the camera body to which the interchangeable lens is attached.

[0026] The barrel of the interchangeable lens 221 houses a photographic optical system including a variable magnification lens 232, an aperture device 100 of the first embodiment for narrowing the optical path, and a focusing lens 229.

[0027] The image sensor 225, composed of photoelectric conversion elements such as a CCD sensor or CMOS sensor, is located inside the camera body and outputs an electrical signal by photoelectric conversion of the subject image formed by the interchangeable lens 221. By changing the aperture opening of the aperture device 100 or moving an ND filter (not shown) forward or backward, 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.

[0028] 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 steps. This generates an image signal. The user can perform zooming by rotating the zoom ring 231 to move the variable magnification lens 232. The controller 222 detects the contrast of the image signal and controls the focus motor 228 according to the contrast to move the focus lens 229 and perform autofocus. Alternatively, the controller 222 may control the focus motor 228 and move the focus lens 229 to perform autofocus based on the detection signal of a focus detection means using a phase difference detection method (not shown).

[0029] Furthermore, the controller 222 controls the drive unit 5 of the aperture device 100 to adjust the amount of light based on the photometric value of a photometric means (not shown) or the image signal. This makes it possible to create natural-looking bokeh and ghosting during shooting and record high-quality images.

[0030] Furthermore, the present invention is not limited to the single-lens reflex cameras described above, but can be broadly applied to optical equipment such as digital cameras with integrated lenses and video cameras. [Explanation of Symbols]

[0031] 101 Drive unit 102 Opening forming member 102b Mounting shaft 103 Pinion 104 Two-stage gear 105 Drive Ring 105b Cam groove 105c Gear section 105d Locking part 106 Torsion coil spring 107 aperture blades 107a Mounting hole 107b Campin 107c Outer edge 108 Cover component

Claims

1. An opening-forming member having an opening that allows light to pass through, A plurality of wing members that move in and out of the opening of the opening forming member, A drive ring that provides driving force to the plurality of blade members, The drive ring comprises a plurality of biasing members that bias each of the plurality of vane members, The vane drive device is characterized in that the plurality of biasing members are a plurality of torsion springs, each having one arm that is locked to a locking portion provided on the drive ring.

2. The system comprises a cover member attached to the opening forming member. The vane drive device according to claim 1, characterized in that the other arm portion of the plurality of torsion springs is positioned inside the hole provided in the cover member.

3. An optical device comprising a blade drive device according to claim 1 or 2, and an image sensor for imaging light that has passed through the opening.

Images