Light quantity adjustment device and optical device

Abstract

To realize technique capable of miniaturizing a beam limiting device and precisely adjusting the quantity of light.SOLUTION: A light quantity adjustment device 100 includes: an opening forming member 103 for forming an opening through which light passes; a turning member 104 that is rotated around the opening on one surface of the opening forming member 103; an energizing pinion gear 102 that has an energizing gear having an energizing mechanism in the turning member 104 and has an energizing mechanism connected to the energizing gear by a gear; and a drive section 101 for driving the turning member 104 by connection. Gear connection is energized in the direction of a light axis to the drive section side by a spring 101m for energizing an output shaft equipped in the drive section 101, and the turning member 104 is energized in the direction of the light axis to the drive section side.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a light amount adjusting device and an optical device mounted on a digital camera or the like.

Background Art

[0002] Conventionally, as a technology in such a field, for example, there is the following Patent Document 1. In this Patent Document 1, by biasing one end of the output shaft of a stepping motor, a pinion gear attached to the output shaft and a drive member for driving a diaphragm blade are biased so as to eliminate backlash, and high-precision light amount adjustment is achieved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, with the configuration of Patent Document 1, the biasing direction of the drive member is away from the stepping motor, which causes an increase in the size of the diaphragm device in the optical axis direction. The present invention realizes a technology capable of adjusting the light amount with high precision while miniaturizing the diaphragm device.

Means for Solving the Problems

[0005] In order to solve the above problems, the light quantity adjusting device of the present invention includes an opening forming member that forms an opening through which light passes, a rotating member that rotates around the periphery of the opening on one surface of the opening forming member, the rotating member has a biasing gear provided with a biasing mechanism, a biasing pinion gear having a biasing mechanism that is gear-connected to the biasing gear, and a driving unit that drives the rotating member by connection. The gear connection is biased in the optical axis direction toward the driving unit side by a spring that biases the output shaft provided in the driving unit, and the rotating member is biased in the optical axis direction toward the driving unit side.

Advantages of the Invention

[0006] By using a spring provided inside the stepping motor to bias the gears against each other, biasing in the opposite direction can be achieved, and miniaturization of the aperture device can be accomplished.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0009] (Example 1) FIG. 1 shows an exploded perspective view of a diaphragm device 100 as an example of a light quantity adjustment device according to an embodiment of the present invention. A stepping motor (drive unit) 101 serving as a drive source for driving the light quantity adjustment device is attached to a base member 103 as an opening forming member having an opening 103a formed at the center thereof.

[0010] FIG. 2 shows an exploded perspective view of the stepping motor 101. 101b is a motor shaft made of a non-magnetic material such as stainless steel that is rotatably supported by bearings 101i and 101j. The rotor 101k is composed of a motor shaft (rotating shaft) 101b and magnets 101a that are alternately magnetized in the circumferential direction. 101c and 101d are inner yokes made of, for example, a soft magnetic material and having a plurality of comb teeth alternately arranged in the circumferential direction. 101g and 101h are outer yokes made of, for example, a soft magnetic material and having a plurality of comb teeth alternately arranged in the circumferential direction. The exciting coils 101e and 101f are mounted between the inner yokes 101c and 101d and the outer yokes 101g and 101h to excite the yokes. The bearings 101i and 101j are coaxially positioned by the outer diameter of the hollow cylindrical portion and the inner diameter of the outer yokes 101g and 101h. Also, both ends of the motor shaft 101b of the rotor 101k are received by the bearings 101i and 101j, and among them, the shaft end on the bearing 101j side is in contact with the pressing plate 101l. The bearing 101i is provided with a spring arrangement surface that receives the biasing force of the coil spring 101m. A coil spring 101m (spring) is arranged between the rotor 101k and the bearing 101i so as to pass through the shaft 101b. Here, the spring arrangement surface receives the biasing force of the coil spring 101m via a washer 101n arranged between the coil spring 101m, and is compressed and held between the rotor 101k and the bearing 101i via a washer 101o on the rotor 101k side. That is, between the bearing 101i and the rotor 101k, a washer 101n, a coil spring 101m, and a washer 101o are arranged in this order from the bearing 101i side, and the coil spring 101m is compressed and held between the bearing 101i and the rotor 101k (magnet 101a). At this time, a force acts to reduce the play between the rotor 101k and the bearing 101i. Therefore, even when receiving vibration, it has a structure in which noise is less likely to occur. In this embodiment, washers 101n and 101o are interposed between the bearing 101i and the coil spring 101m and between the coil spring 101m and the rotor 101k, respectively, but the washers 101n and 101o may not be interposed.Also, the bearing 101i is provided with a recess in which one end side of the coil spring 101m is partially accommodated, and the coil spring 101m is held within this recess. As a result, a preload is applied in the axial direction to the rotor 101k, suppressing the vibration (flutter) of the rotor 101k, and enhancing the quietness of the motor. The spring arrangement surface of the bearing 101i may be formed by being recessed or protruding with respect to the end surface of the bearing 101i. Recessing is preferable because the natural length of the spring can be set longer, reducing the spring constant. A pinion 102 is attached to the rotating shaft of the stepping motor 101.

[0011] FIG. 3 shows a perspective view of the pinion 102. The pinion 102 is formed by resin molding in this embodiment, for example. Also, the gear portion of the pinion is configured in a bevel gear shape. The base member 103 is formed by resin molding in this embodiment, for example, and has a plurality of engagement pins 103c.

[0012] FIG. 4 shows a perspective view of the rotating member 104. The rotating member 104 (drive ring) for driving the throttle blade 105 is provided on the base member 103, and is, for example, a circular sheet-like member formed by resin molding in this embodiment, and a circular opening serving as a light passage path through which light passes is formed in the central portion thereof. This rotating member 104 has a plurality of drive pins 104d erected thereon, a driven portion 104e provided at the outer peripheral end to which the pinion gear 102 is connected, and a light-shielding portion 104f provided to partially protrude at the outer peripheral end.

[0013] Here, the rotating member 104 is created, for example, by pressing a resin film (such as a PET sheet material). When the rotating member 104 is made of a resin film, it can be made thin and light. Also, when the rotating member 104 is made of a resin film, the part that guides the operation of the rotating member 104 does not require as much strength as when the rotating member is created by resin molding. For example, it is possible to guide the rotating member 104 with a thin guide pin that guides the throttle blade. When it can be press-processed, the shape accuracy can be formed with higher precision compared to the shape accuracy of resin molding, so the throttle accuracy can be increased. Of course, the rotating member 104 does not have to be formed by a thin sheet-like member and can also be formed by resin molding.

[0014] Also, the rotating member 104 has a bevel gear part that is the driven part 104e. This driven part 104e meshes with the pinion 102. The rotational force generated by the stepping motor 101 is transmitted from the pinion 103 to the driven part 104e, causing the rotating member 104 to rotate. Also, 104f is a light-shielding part. The light-shielding part 104f enters and exits the slit of the photo interrupter 107, serving as a sensor that detects the rotational position of the rotating member 104. It is used for position detection such as the initial position of the light quantity adjustment device.

[0015] In this embodiment, a plurality (seven) of throttle blades 105 are arranged in a ring so as to surround an opening through which light passes. Each throttle blade 105 is formed with an engagement hole 105d and a cam groove 105c, which are driven parts. Such throttle blades 105 may be created, for example, by pressing a PET sheet material or the like, or by resin molding or the like. Also, the number of throttle blades may be any configuration as long as it is three or more. In this embodiment, in order to increase the roundness of the throttle opening, it is composed of seven throttle blades. In this embodiment, a plurality of throttle blades 105 form a blade group. In particular, the plurality of throttle blades 105 are woven so as to be sandwiched between adjacent throttle blades 105.

[0016] As a cover member 106 serving as the other aperture forming member, between it and the base member 103, it houses the plurality of aperture blades 105 and the rotating members 104 for driving these blades described above, and forms a blade chamber in which the blades travel between it and the rotating members 104. That is, in the blade chamber (driving space) formed by the base member 103 and the cover member 106, the plurality of aperture blades 105 travel (are driven) along with the rotation of the rotating member 104. An opening 106a communicating with the opening of the base member 103 is formed in this cover member 106, and like the base member 103, it serves as an aperture forming member. The cover member 106 is created by resin molding or by pressing a PET sheet material or the like.

[0017] The engaging hole 105d of the aperture blade 105 engages with the driving pin 104d of the rotating member 104. When the pinion 102 rotates, a force is applied to the driven part 104e of the rotating member 104, and the rotating member 104 rotates. Then, a driving force is applied from the driving pin 104d of the rotating member 104 to the engaging hole 105d of the aperture blade 105, and the aperture blade 105 is driven. At this time, the cam groove 105c of the aperture blade 105 engages with the engaging part 103c of the base member 103. Therefore, due to the cam groove 105c, the aperture blade 105 enters and exits the inside and outside of the opening 103a of the base member 103. Thereby, it becomes possible to adjust the aperture shape (the diameter of the aperture opening) of the plurality of aperture blades 105 within the opening 102a of the base member 103 and adjust the amount of light passing through. In this embodiment, the aperture blade 105 in which seven blades are woven together to form an aperture opening is illustrated and described, but it may also be variously applied as a blade driving device for other shutter blades or blades having an optical filter. The maximum opening of the portion through which light passes may be defined by the opening 106a of the base member 103 or the cover member 106, or may be defined by the ends of the plurality of aperture blades 105. In this embodiment, the maximum opening is defined by the opening 106a of the cover member 106.

[0018] Figure 5 is a relational diagram of the stepping motor, pinion, and rotating member. It shows the meshing part between the bevel gear part which is the driven part 104e and the pinion 102. As shown in Figure 5, the pinion 102 is biased toward the stepping motor 101 by the coil spring 13 inside the stepping motor 101. Further, when the pinion 102 is biased, the rotating member 104 that meshes with the pinion 102 is also biased in the optical axis direction.

[0019] Figure 6 shows the relationship between the pinion 102 and the bevel gear part which is the driven part 104e of the rotating member 104. Since the pinion 102 meshes with the driven part 104e in a state biased in the optical axis direction, backlash is reduced and the light amount can be adjusted with high precision.

[0020] Also, according to the present embodiment, since the rotating member 104 is biased toward the stepping motor, the space in the optical axis direction for accommodating the rotating member 104 can be reduced. That is, it is possible to miniaturize the aperture device 100.

[0021] (Example 2) Figure 7 shows the internal configuration of an interchangeable lens 221 for a single-lens reflex camera as an imaging device equipped with the aperture device described in Example 1, and the camera body to which the interchangeable lens is attached.

[0022] Inside the lens barrel of the interchangeable lens 221, an imaging optical system including a zoom lens 232, the aperture device 100 of the first embodiment that narrows the optical path, and a focus lens 229 is accommodated.

[0023] An image sensor 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 sensor 225 (that is, the amount of light reaching the image sensor 225) can be appropriately set.

[0024] 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.

[0025] 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.

[0026] Furthermore, the controller 222 controls the drive unit 5 of the diaphragm device 100 based on the photometry value of a photometry means (not shown) or the image signal to adjust the amount of light. Thereby, blurring and ghosting during shooting can be made into natural shapes, and high-quality images can be recorded.

[0027] 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 a lens-integrated digital camera and a video camera.

Explanation of Signs

[0028] 101 Stepping motor (drive unit) 101m Coil spring (spring) 102 Pinion 103 Base member 104 Rotating member 104e Driven part 105 Diaphragm blade 106 Cover member

Claims

1. An aperture forming member that forms an aperture through which light passes, A rotating member that rotates around the periphery of the aperture on one surface of the aperture forming member, The rotating member has a biasing gear provided with a biasing mechanism, A biasing pinion gear having a biasing mechanism that is gear-connected to the biasing gear, A drive unit that drives the rotating member by connection, and is provided with, A spring that biases the output shaft provided in the drive unit biases the gear connection in the optical axis direction on the drive unit side, and biases the rotating member in the optical axis direction on the drive unit side. A light quantity adjustment device characterized by being.

2. An optical device comprising the light quantity adjustment device according to claim 1 and an imaging element that images light that has passed through the light quantity adjustment device.

Images