JP2025087101A - Light control devices and optical instruments - Google Patents

Abstract

[Problem] The present invention realizes a technology that can adjust the amount of light with high precision while miniaturizing the aperture device. [Solution] In order to solve the above problem, the light amount adjustment device 100 of the present invention comprises an aperture forming member 103 that forms an aperture through which light passes, a rotating member 104 that rotates around the aperture on one side of the aperture forming member 103, a biasing gear provided with a biasing mechanism on the rotating member 104, a biasing pinion gear 102 that has a biasing mechanism that is gear-connected with the biasing gear, and a drive unit 101 that drives the rotating member 104 by connection, and is characterized in that the gear connection is biased toward the drive unit in the optical axis direction by a spring 101m that biases the output shaft provided on the drive unit 101, and the rotation member 104 is biased toward the drive unit in the optical axis direction. [Selected Figure] Figure 5

Description

The present invention relates to a light amount adjustment device and optical equipment mounted on digital cameras and the like.

As an example of a conventional technology in this field, there is the following Patent Document 1. In this Patent Document 1, by energizing one end of the output shaft of a stepping motor, a pinion gear attached to the output shaft and a driving member that drives the aperture blades are energized, thereby eliminating backlash and achieving high precision in adjusting the amount of light.

JP 2009-180921 A

However, with the configuration of Patent Document 1, the driving member is biased in a direction away from the stepping motor, which leads to an increase in size of the aperture device in the optical axis direction. The present invention realizes technology that can adjust the amount of light with high precision while miniaturizing the aperture device.

In order to solve the above problem, the light amount adjustment device of the present invention comprises an opening forming member that forms an opening through which light passes, a rotating member that rotates around the opening on one side of the opening forming member, a biasing gear provided with a biasing mechanism on the rotating member, a biasing pinion gear having a biasing mechanism that is gear-connected to the biasing gear, and a drive unit that drives the rotating member by connecting them, and is characterized in that the gear connection is biased in the optical axis direction toward the drive unit by a spring that biases the output shaft provided in the drive unit, and the rotating member is biased in the optical axis direction toward the drive unit.

By using a spring inside the stepping motor to bias the gears together, they can be biased in opposite directions, making it possible to miniaturize the aperture device.

1 is an exploded perspective view of a light amount adjustment device according to an embodiment of the present invention; Exploded perspective view of a stepping motor Cross section of a pinion FIG. Diagram of the relationship between stepping motor, pinion and rotating member Diagram of the relationship between the pinion and rotating parts Schematic diagram of an imaging device equipped with a light amount adjustment device.

The following describes in detail an embodiment of the present invention with reference to the drawings.

Example 1
1 shows an exploded perspective view of an aperture device 100 as a light amount adjusting device, which is an example of a light amount adjusting device according to an embodiment of the present invention. A stepping motor (drive unit) 101, which serves as a drive source for driving the light amount adjusting device, is attached to a base member 103, which serves as an aperture forming member, and has an aperture 103a formed in the center.

Figure 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, which is supported rotatably by bearings 101i and 101j. The rotor 101k is composed of the motor shaft (rotating shaft) 101b and a magnet 101a magnetized alternately in the circumferential direction. 101c and 101d are inner yokes made of, for example, a soft magnetic material, having multiple comb teeth arranged alternately in the circumferential direction. 101g and 101h are outer yokes made of, for example, a soft magnetic material, having multiple comb teeth arranged alternately in the circumferential direction. The excitation 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. In addition, both ends of the motor shaft 101b of the rotor 101k are supported by bearings 101i and 101j, and the shaft end on the bearing 101j side is abutted against a pressing plate 101l. The bearing 101i is provided with a spring arrangement surface that receives the biasing force of the coil spring 101m. The coil spring 101m (spring) is arranged between the rotor 101k and the bearing 101i so that it passes 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, the washer 101n, the coil spring 101m, and the 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 that reduces the backlash between the rotor 101k and the bearing 101i works. Therefore, even if vibration is applied, the structure is unlikely to generate noise. In this embodiment, the 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 do not have to be interposed. In addition, 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 to the rotor 101k in the axial direction, suppressing vibration (fluttering) of the rotor 101k and improving the quietness of the motor. The spring arrangement surface of the bearing 101i may be recessed or protruded from the end face of the bearing 101i. A recessed surface is preferable because it allows the natural length of the spring to be set longer, reducing the spring multiplier. A pinion 102 is attached to the rotating shaft of the stepping motor 101.

Figure 3 shows a perspective view of the pinion 102. In this embodiment, the pinion 102 is formed, for example, by resin molding. The gear portion of the pinion is configured with bevel teeth. In this embodiment, the base member 103 is formed, for example, by resin molding, and has multiple engagement pins 103c.

Figure 4 shows a perspective view of the rotating member 104. The rotating member 104 (drive ring) for driving the aperture blades 105 is provided on the base member 103, and in this embodiment, for example, is a circular sheet-like member formed by resin molding, with a circular opening formed in the center as a light passage through which light passes. This rotating member 104 has a number of upright drive pins 104d, a driven portion 104e provided at the outer periphery end to which the pinion gear 102 is connected, and a light-shielding portion 104f partially protruding from the outer periphery end.

Here, the rotating member 104 is made by, for example, pressing a resin film (such as a PET sheet material). When the rotating member 104 is made of a resin film, the rotating member 104 can be made thin and lightweight. Furthermore, when the rotating member 104 is made of a resin film, the portion that guides the operation of the rotating member 104 does not need to be as strong as when the rotating member is made by resin molding. For example, the rotating member 104 can be guided by a thin guide pin like the one that guides the aperture blades. When the rotating member 104 can be pressed, the shape can be formed with high precision compared to the shape precision of resin molding, so that the aperture precision can be made high. Of course, the rotating member 104 does not have to be formed from a thin sheet-like material, and can be formed by resin molding.

The rotating member 104 also has a bevel gear portion which is the driven portion 104e. This driven portion 104e meshes with the pinion 102. The rotational force generated by the stepping motor 101 is transmitted from the pinion 103 to the driven portion 104e, which causes the rotating member 104 to rotate. 104f is a light blocking portion. The light blocking portion 104f moves in and out of the slit of the photointerrupter 107, thereby acting as a sensor that detects the rotational position of the rotating member 104. It is used to detect the initial position of the light adjustment device, etc.

In this embodiment, multiple (seven) aperture blades 105 are arranged in a ring shape to surround the aperture through which light passes. Each aperture blade 105 is formed with an engagement hole 105d and a cam groove 105c, which are driven parts. Such aperture blades 105 may be made, for example, by pressing a PET sheet material or the like, or by resin molding or the like. The number of aperture blades may be any number greater than or equal to three, and in this embodiment, seven aperture blades are used to increase the circularity of the aperture opening. In this embodiment, the multiple aperture blades 105 form a blade group. In particular, the multiple aperture blades 105 are woven so that they are sandwiched between adjacent aperture blades 105.

The cover member 106, which serves as the other aperture forming member, houses the above-mentioned multiple aperture blades 105 and the rotating member 104 for driving these blades between the base member 103 and forms a blade chamber in which the blades run between the rotating member 104. That is, the multiple aperture blades 105 run (drive) in the blade chamber (drive space) formed by the base member 103 and the cover member 106 as the rotating member 104 rotates. This cover member 106 is formed with an opening 106a that communicates with the opening of the base member 103, and is an opening forming member like the base member 103. The cover member 106 is made by molding resin or pressing a PET sheet material or the like.

The engagement hole 105d of the aperture blade 105 engages with the drive pin 104d of the rotating member 104. When the pinion 102 rotates, a force is applied to the driven portion 104e of the rotating member 104, causing the rotating member 104 to rotate. Then, a driving force is applied from the drive pin 104d of the rotating member 104 to the engagement hole 105d of the aperture blade 105, driving the aperture blade 105. At this time, the cam groove 105c of the aperture blade 105 engages with the engagement portion 103c of the base member 103. Therefore, the cam groove 105c allows the aperture blade 105 to move in and out of the opening 103a of the base member 103. This allows the multiple aperture blades 105 to adjust the aperture shape (diameter of the aperture opening) in the opening 102a of the base member 103, and adjust the amount of light passing through. In this embodiment, the aperture blade 105 is described as an example in which seven blades are woven together to form the aperture opening, but other types of shutter blades or blades with optical filters may also be used as blade drive devices. The maximum opening through which light passes may be determined by the opening 106a of the base member 103 or cover member 106, or may be determined by the ends of the multiple aperture blades 105. In this embodiment, the maximum opening is determined by the opening 106a of the cover member 106.

Figure 5 is a diagram showing the relationship between the stepping motor, pinion, and rotating member. It shows the bevel gear portion, which is the driven portion 104e, and the meshing portion with 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. In addition, as the pinion 102 is biased, the rotating member 104 that meshes with the pinion 102 is also biased in the optical axis direction.

Figure 6 shows the relationship between the pinion 102 and the bevel gear portion, which is the driven portion 104e of the rotating member 104. The pinion 102 meshes with the driven portion 104e while being biased in the optical axis direction, reducing backlash and enabling the light quantity to be adjusted with high precision.

In addition, according to this embodiment, since the rotating member 104 is biased toward the stepping motor, the space required in the optical axis direction to accommodate the rotating member 104 can be reduced. In other words, the aperture device 100 can be made more compact.

Example 2
FIG. 7 shows an interchangeable lens 221 for a single-lens reflex camera, serving as an imaging device equipped with the diaphragm device described in the first embodiment, and the internal configuration of a camera body to which the interchangeable lens is attached.

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

The image sensor 225, which is composed of photoelectric conversion elements such as a CCD sensor or a CMOS sensor, is disposed in the camera body and photoelectrically converts the subject image formed by the interchangeable lens 221 to output an electrical signal. By changing the aperture of the diaphragm 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.

The electrical signal output from the image sensor 225 is converted to a digital signal in the image processing circuit 226 and undergoes various image processing. This generates an image signal.

By rotating the zoom ring 231, the user can move the variable magnification lens 232 to change the magnification (zooming). The controller 222 detects the contrast of the image signal, controls the focus motor 228 in accordance with the contrast, and moves the focus lens 229 to perform autofocus. Alternatively, the controller 222 may control the focus motor 228 and move the 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).

Furthermore, the controller 222 controls the driver 5 of the aperture device 100 based on the photometric value of a photometric means (not shown) or an image signal to adjust the amount of light. This makes it possible to make the blur and ghosting that occurs during shooting appear natural, allowing high-quality images to be recorded.

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 integrated lenses and video cameras.

101 Stepping motor (drive unit)
101m coil spring
102 pinion 103 base member 104 rotating member 104e driven part 105 aperture blade 106 cover member

Claims (2)

an aperture forming member that forms an aperture through which light passes;
a rotating member that rotates around the opening on one surface of the opening forming member;
The rotating member has a biasing gear equipped 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 coupling,
A light intensity adjustment device characterized in that the gear connection is urged toward the drive unit in the optical axis direction by a spring that urges an output shaft provided in the drive unit, and the rotating member is urged toward the drive unit in the optical axis direction. 13. An optical device comprising: the light amount adjusting device according to claim 1; and an imaging element for imaging light that has passed through the light amount adjusting device.

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