Blade driving device and imaging apparatus

Abstract

To suppress a change in blade overlapping amount in an optical axis direction during opening / closing operation of a blade driving device, a posture difference caused by the backlash setting in the optical axis direction of a component, an optical performance change caused by a fall of a blade, and an increase in warpage of the blade.SOLUTION: The blade driving device is a blade driving device 10 for adjusting the size of an opening through which light passes by a plurality of diaphragm blades 2 and includes a driving ring 3 for driving the diaphragm blades 2, and a partition member 5 for partitioning between the diaphragm blades 2 and the driving ring 3. The partition member 5 has slope parts 52a to 52c. The slope parts 52a to 52c energize the driving ring 3 in a light-passing direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a blade driving device such as a diaphragm device, and an imaging device such as a camera including the blade driving device.

Background Art

[0002] Generally, a blade driving device for driving blades includes a base member having an opening corresponding to an imaging optical path, a plurality of diaphragm blades supported by the base member and operating to open and close the opening, and a driving ring that rotates with respect to the base member. It is known that a series of diaphragm operations from full open to minimum aperture are performed by opening and closing the plurality of blades by the driving ring.

[0003] In the blade driving device disclosed in Patent Document 1, in a blade driving device including a ring-shaped base member having an optical path opening, a guide member provided to face the base member, and a plurality of diaphragm blades that slide in the circumferential direction while overlapping each other in a sliding space provided between the base member and the guide member and open and close the optical path opening, in conjunction with the sliding of the plurality of diaphragm blades, an interval changing means for changing the interval of the sliding space between the base member and the guide member is provided.

[0004] According to the blade driving device of Patent Document 1, in conjunction with the sliding of the plurality of diaphragm blades when closing the optical path opening, the sliding space between the base member and the guide member can be appropriately changed according to the overlap of the diaphragm blades. As a result, the load torque associated with the opening and closing operation of the plurality of diaphragm blades can be minimized and made constant between the open side and the minimum aperture side of the optical path opening, and a series of diaphragm operations from full open to minimum aperture can be performed smoothly.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a structure such as the blade driving device of Patent Document 1, when opening the aperture, the plurality of aperture blades forming the aperture overlap the most in the sliding space in the optical axis direction formed between the base member and the guide member, and as the aperture is narrowed, the overlap of each aperture blade gradually decreases. Since the sliding space of the aperture blades is set according to the open side where the number of overlapping aperture blades increases, when gradually narrowing from the open side, the overlap of the blades decreases, resulting in a change in the space occupied by the aperture blades in the optical axis direction in the sliding space.

[0007] Also, in a structure such as the blade driving device of Patent Document 1, generally, in consideration of the finish of parts and dimensional changes due to environmental changes, the guide member is configured to have play (about 0.1 mm) in the optical axis direction.

[0008] In the above prior art, during the opening and closing operation, by changing the interval of the sliding space in conjunction with the sliding of the aperture blades, the operating load torque can be driven to be constant. However, on the small aperture side, the interval must be widened to reduce the operating torque, resulting in a difference in the space occupied by the aperture blades in the optical axis direction between the open state and the minimum aperture state in the sliding space of the aperture blades between the base member and the guide member. In particular, in the minimum aperture state where the space occupied by the aperture blades in the optical axis direction is small, for example, performance changes due to posture fluctuations occur. Moreover, in consideration of the finish of parts and dimensional changes of parts due to environmental changes, since the guide member is configured to have play in the optical axis direction, as the aperture blades enter the small aperture state, the aperture blades compete with each other and tilt, resulting in an increase in warping.

[0009] Therefore, in the above prior art, as the inclination of the aperture blades increases, the aperture formed by the aperture blades moves in the optical axis direction, resulting in over-aperturing beyond the assumed aperture diameter, or conversely, due to intense competition between the aperture blades making it impossible to close the aperture, performance changes occur. Also, since the amount of warping of the blades increases, the space in the optical axis direction of the blade driving device increases.

Means for Solving the Problems

[0010] In order to solve the above problems, the blade driving device of the present invention is a blade driving device that adjusts the size of an opening through which light passes by a plurality of aperture blades, and includes a driving ring that drives the aperture blades, and a partition member that partitions between the aperture blades and the driving ring. The partition member has an inclined surface, and the inclined surface biases the driving ring in the light passing direction.

Effects of the Invention

[0011] The present invention reduces the influence of posture fluctuations due to changes in the overlap of the aperture blades during the opening and closing operations, the influence of performance changes due to the inclination of the blades caused by the backlash setting of the components in the optical axis direction, and the amount of warping. It can more stably determine the aperture size from the open state to the minimum aperture, and provides a blade driving device with reduced space in the optical axis direction in the small aperture state.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiment for Carrying out the Invention

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

[0014] <Example 1> FIGS. 1 and 2 are exploded views showing the configuration of the blade drive device 10 of Example 1 according to the present invention shown in FIG. 5. This blade drive device 10 includes an optical path opening 11 centered on the optical axis, a base member 1 having opening and closing guide cams 1a to 1i, a plurality of aperture blades 2, a drive plate 3 (drive ring) for driving the aperture blades 2 to open and close, a cover member 4 with which the drive plate 3 is slidably abutted, and a partition member 5 having an optical path opening 51 with a size equal to or larger than that of the base member 1 between the aperture blades 2 and the drive plate 3."

[0015] The drive base member 1 is generally created by resin molding. The base member 1 is a ring-shaped member forming the opening 11, and has protrusions 12a to 12i serving as a plurality of support portions for supporting the partition member 5 and forming a sliding space A for the aperture blades 2, and a plurality of opening and closing guide cams 1a to 1i corresponding to the number of aperture blades 2."

[0016] The opening and closing guide cams 1a to 1i are engaged with cam pins 21b to 29b provided on one of the base portions 21a to 29a of the aperture blades 2. By moving the cam pins 21b to 29b along the opening and closing guide cams 1a to 1i, the aperture blades can be opened and closed."

[0017] The drive plate 3 is generally formed in a ring shape by resin molding. A gear 3j is formed on a part of the outer peripheral portion of the drive plate 3 and meshes with a rotating gear 7 of a drive motor 6 attached to the cover member 4 to drive it in rotation. The drive motor 6 can rotate clockwise and counterclockwise. Due to the rotation of the drive motor 6, the drive plate 3 rotates within a set rotation range. In the plurality of rotary shaft holes 3a to 3i, drive pins 21c to 29c provided on the opposite side to the cam pins 21b to 29b of the plurality of aperture blades 2 engage with each other, thereby opening and closing the aperture blades and adjusting the light amount by changing the aperture.

[0018] The aperture blades in this embodiment are composed of nine aperture blades 21 to 29, and the cam pins 21b to 29b and the drive pins 21c to 29c are provided on each blade. The bases 21a to 29a of the respective aperture blades are arranged at equal angular intervals around the optical axis, and a part of the blades overlap each other to form an aperture on the inner peripheral side of the aperture blade 2. Then, by the rotation of the drive ring 3, the overlap between the blades changes, thereby continuously changing the size of the aperture.

[0019] The aperture blade 2 has the drive pins 21c to 29c and the cam pins 21b to 29b attached to the blade bases 21a to 29a. The aperture blade 2 is integrally formed by resin molding with the blade bases 21a to 29a, the drive pins 21c to 29c, and the cam pins 21b to 29b.

[0020] Also, for the aperture blade 2, the blade bases 21a to 29a can be created by a light-shielding treated sheet member, and the drive pins 21c to 29c and the cam pins 21b to 29b can be created by resin molding and integrated with the blade bases 21a to 29a by adhesion, welding, outsert molding, etc. Further, the drive pins 21c to 29c and the cam pins 21b to 29b can be formed of metal pins and integrated with the blade bases 21a to 29a by adhesion, welding, caulking, etc.

[0021] The cover member 4 has a fitting hole 4j for attaching the drive motor 6, and may be provided with an attachment shape when the blade drive device 10 is incorporated into the imaging device. Similar to the drive plate 3, it is formed in a ring shape by resin molding, and the drive plate 3 is rotatably supported by the sliding of the protruding portions 4a to 4h provided in the circumferential direction on the inner diameter side and the outer peripheral portion 31 of the drive plate 3.

[0022] The partition member 5 has an opening at the center. The partition member 5 is supported in the radial direction by the engagement of the engagement hole 50 of the partition member 5 with the engagement portion 40 of the cover member 4, and is clamped in the thrust direction by the plurality of protrusions 12a to 12i of the base member 1 and the plurality of support portions 41a to 41i of the cover member 4.

[0023] Since the partition member 5 can hold down the cam pins 21b to 29b of the aperture blades 2, it is possible to prevent the cam pins 21b to 29b from falling off from the opening / closing guide cams 1a to 1i of the base member 1. Further, since the drive plate 3 is clamped by the rail 401 of the partition member 5 and the cover member 4, the drive plate 3 only needs to have the minimum outer shape that can be clamped. Therefore, the drive plate 3 can be miniaturized, reducing the inertia during rotation, which is effective for high-speed driving. The partition member 5 is made, for example, by pressing a resin film (such as a PET sheet material).

[0024] In the blade driving device of the present invention, inclined surfaces 52a to 52c are provided on the partition member 5. The drive plate 3 is incorporated such that the sliding protrusion shapes 301a to 301c of the drive plate 3 contact the surface of the partition member 5 on the cover member 4 side, and the sliding protrusion shapes 310a to 310c of the drive plate 3 contact the surface of the partition member 5 on the base member 1 side. As the drive plate 3 rotates while contacting the inclined surfaces 52a to 52c of the partition member 5, it is biased toward the base member 1 side in the optical axis direction (light passing direction) as it progresses from the open state to the small aperture state. Therefore, play in the optical axis direction of the drive plate 3 can be eliminated, and problems such as performance changes due to posture fluctuations, performance changes due to blade inclination, and an increase in the amount of upward warping of the aperture blades, which were caused by the space difference in the optical axis direction occupied by the aperture blades due to changes in the overlap of the aperture blades during the opening and closing operations and play in the guide member, can be improved.

[0025] The inclined surfaces 52a to 52c of the partition member 5 are formed as bent shapes when the partition member 5 is created by pressing.

[0026] The inclined surfaces 52a to 52c of the partition member 5 and the sliding protrusion shapes 301a to 301c and 310a to 310c of the drive plate 3 are preferably arranged at three or more positions and at equal angular intervals in order to stably support the drive plate 3.

[0027] As described above, in the blade driving device 10 of the present invention, the change in the space occupied by the aperture blade 2 in the optical axis direction in the sliding space is minimized due to the change in the overlap of the aperture blade 2 in the aperture operation of the optical path opening 11, and the increase in the inclination of the blade due to the play of the drive plate 3 can be suppressed. Therefore, it is possible to suppress the influence on the performance due to the posture difference fluctuation in the state where the overlap of the aperture blades is small, the performance change due to the inclination of the blades, and the increase in the amount of warping of the blades. In this way, the posture difference fluctuation is suppressed from the open state to the minimum aperture state of the optical path opening, and the opening and closing operation can be stably performed. Therefore, the light amount adjustment by an imaging device such as a camera can be accurately performed. Also, by suppressing the inclination of the blades, the space in the optical axis direction of the blade driving device can be reduced, and the degree of freedom in the interval between the optical lenses arranged before and after the blade driving device is also generated, so that the optical performance can be improved. Further, since the configuration is simple only by bending a part of the shape of the partition member, the countermeasure cost can be kept low.

[0028] <Example 2> FIG. 6 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 embodiment 1, and the camera body to which the interchangeable lens is attached.

[0029] Inside the lens barrel of the interchangeable lens 221, a photographing optical system including a zoom lens 232, an aperture device 100 of the first embodiment for narrowing the optical path, and a focus lens 229 is accommodated.

[0030] An image pickup device 225 composed of a photoelectric conversion element such as a CCD sensor or a CMOS sensor is arranged inside the camera body, and photoelectrically converts the subject image formed by the interchangeable lens 221 to output an electrical signal. By changing the aperture opening of the aperture device 100 or moving a non-illustrated ND filter forward and backward, the brightness of the subject image formed on the image pickup device 225 (that is, the amount of light reaching the image pickup device 225) can be appropriately set.

[0031] The electrical signal output from the imaging element 225 is converted into a digital signal in the image processing circuit 226 and subjected to various image processes. Thereby, an image signal is generated.

[0032] The user can move the zoom lens 232 by rotating the zoom ring 231 to perform zooming. The controller 222 detects the contrast of the image signal, controls the focus motor 228 according to the detected contrast, and moves the focus lens 229 to perform autofocus. Alternatively, the controller 222 may control the focus motor 228 based on the detection signal of a focus detection means using a phase difference detection method (not shown) to move the focus lens 229 to perform autofocus.

[0033] Furthermore, the controller 222 controls the drive unit 5 of the aperture device 100 based on the photometry value of a photometry means (not shown) or the image signal to adjust the light amount. Thereby, blurring and ghosting during shooting can be made into natural shapes, and high-quality images can be recorded. Note that the present invention is not limited to the above-described single-lens reflex camera, and can be widely applied to optical devices such as lens-integrated digital cameras and video cameras.

Explanation of Reference Numerals

[0034] 1 Base member 2 Aperture blade 3 Drive plate (drive ring) 4 Cover member 5 Partition member 6 Drive unit 7 Pinion

Claims

1. A blade drive device that adjusts the size of an aperture through which light passes by using a plurality of aperture blades, A drive ring that drives the aperture blades; a partition member that separates the aperture blade and the drive ring, The partition member has a slope portion, The blade drive device, wherein the inclined surface portion biases the drive ring in a light transmitting direction.

2. The inclined surface portion is oriented such that the biasing force becomes stronger as the aperture becomes smaller when the driving ring is opened or closed. The blade drive device according to claim 1 .

3. The inclined surface portion is arranged in a circumferential direction. The blade drive device according to claim 1 .

4. The inclined surface portion is provided at three or more locations and is arranged at equal angular intervals in the circumferential direction. The blade drive device according to claim 1 .

5. The inclined surface portion is characterized by having a spring characteristic. The blade drive device according to claim 1 .

6. The inclined surface portion has a spring characteristic, and the spring characteristic is greater than the mass of the drive ring. It is characterized by its strength. The blade drive device according to claim 1 .

7. 7. An optical device comprising: the blade drive device according to claim 1; and an imaging element that images light that has passed through the blade drive device.

Images