Light intensity adjustment device and imaging device

Abstract

To provide a light quantity adjusting device and imaging apparatus advantageous in downsizing.SOLUTION: The light quantity adjusting device includes: a base member having an opening that allows light to pass through; an aperture blade group that narrows the opening; a driving ring that drives the aperture blade group engaged through an engagement portion; and a driving portion that transmits driving force to the driving ring through a driven portion provided in the driving ring. The driving ring has a cylindrical portion between the driven portion and the engagement portion.SELECTED DRAWING: Figure 3A

Description

Technical Field

[0001] The present invention relates to a light quantity adjustment device such as an aperture device, for example, and an imaging device including the same.

Background Art

[0002] Conventionally, as a light quantity adjustment device in an imaging device such as a camera, there is known one including a base plate having an opening for an optical path, a blade supported by the base plate and operating to open and close the opening, and a drive ring that rotates with respect to the base plate (see Patent Document 1).

[0003] In a light quantity adjustment device such as that of Patent Document 1, the drive ring is rotationally driven, and the blade is moved by the further rotating drive ring to open and close the opening for the optical path.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, in light quantity adjustment devices, further miniaturization has been desired due to various demands such as reduction of the mounting space in an imaging device such as a camera to be mounted and cost reduction.

[0006] The present invention has been made in view of the above-described problems, and an object thereof is to provide a light quantity adjustment device and an imaging device advantageous for miniaturization.

Means for Solving the Problems

[0007] The light quantity adjustment device according to the present invention includes a base member having an opening through which light passes, an aperture blade group that narrows the opening, A cam groove is provided, and the cam grooveA drive ring that drives the aperture blade group which engages via and a provided on the drive ring gear The drive unit transmits driving force to the drive ring via the drive ring, and the drive ring is gear and the above Cam groove Between them, there is a cylindrical part. Furthermore, the gear and the cylindrical portion overlap in the direction of light passage. It is characterized by the following: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a light intensity adjustment device and an imaging device that are advantageous for miniaturization. [Brief explanation of the drawing]

[0009] [Figure 1] Exploded perspective view of an aperture device according to Embodiment 1 of the present invention. [Figure 2] A perspective view of the holding substrate used in the diaphragm device of Embodiment 1. [Figure 3A] A perspective view of the drive ring used in the aperture device of Embodiment 1. [Figure 3B] A cross-sectional view of the drive ring used in the throttling device of Embodiment 1. [Figure 3C] A plan view of the drive ring used in the diaphragm device of Embodiment 1. [Figure 4] This figure shows how the drive ring is assembled to the holding substrate in Embodiment 1. [Figure 5] A close-up view of the drive ring during assembly. [Figure 6] A perspective view of the aperture blades used in the aperture device of Embodiment 1. [Figure 7] A perspective view of the aperture-forming member used in the throttling device of Embodiment 1. [Figure 8] A schematic diagram of an imaging device equipped with the aperture device of Embodiment 1. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below with reference to the drawings.

[0011] <Embodiment 1> Figure 1 is an exploded perspective view showing the configuration of an aperture device 100, which is an embodiment 1 of the light intensity control device of the present invention.

[0012] In Figure 1, the retaining substrate 102 has an opening in the center and is a cylindrical member (base member) that serves as the base of the aperture device 100. Figure 2 is a perspective view of the retaining substrate 102. The retaining substrate 102 has a first engaging projection 102a and a second engaging projection 102b that define the rotational position of the drive ring 103 relative to the opening forming member 106, which will be described later. The retaining substrate 102 also has a plurality of engaging pins 102c that engage with a plurality of aperture blades (blade groups) 105. In this embodiment, the retaining substrate 102 is made, for example, by resin molding. A drive unit 101 is attached to the retaining substrate 102. As a drive source for the drive unit 101, for example, a stepping motor or a galvanometer motor is used. A pinion 104 is attached to the rotating shaft 101a of the drive unit 101.

[0013] Figure 3A is a perspective view of the drive ring 103. The drive ring 103 has a through hole 103f that constitutes at least a part of the light passage path, and is formed from an annular member (cylindrical part) that surrounds the path through which light passes (light passage path), and rotates around the light passage path. The aperture blades 105, which will be described later, engage with this drive ring 103. As the drive ring 103 rotates, it causes the aperture blades 105 to move in and out of the light passage path. In other words, the drive ring 103 is a member (power transmission member) for driving the aperture blades 105.

[0014] This drive ring 103 has a base portion 103a, a cam groove (engagement portion) 103b, and a driven portion 103c that receives the driving force from the driving portion 101. The drive ring 103 further has a first engagement ring 103d that slidably contacts the first engagement protrusion 102a of the holding substrate 102, and a second engagement ring 103e that slidably contacts the second engagement protrusion 102b of the holding substrate 102. By making the base portion 103a have a substantially uniform thickness, it is possible to make the drive ring 103 less susceptible to the influence of air resistance when it rotates. Therefore, the operating load can be reduced, and the high-speed responsiveness and quietness can be improved.

[0015] Also, the base portion 103a of the drive ring 103 is surface-treated on one side or both sides. Examples of the surface treatment include sliding coating, antistatic treatment, antireflection treatment, etc. By applying sliding coating, the friction between the drive ring 103 and the holding substrate 102, which is a component that slides with the drive ring 103, and the opening forming member 106 described later can be reduced, and the power consumption of the driving portion 101 can be reduced. Also, by performing antireflection treatment, the reflection of light that has entered the light quantity adjustment device 100 can be suppressed, and the occurrence of ghosts, flares, etc. when the light quantity adjustment device 100 is incorporated into the lens barrel can be suppressed.

[0016] The drive ring 103 also has a driven portion 103c formed with a gear portion. This driven portion 103c meshes with the pinion 104 via an intermediate gear 107. The rotational force generated in the driving portion 101 is transmitted from the pinion 104 to the driven portion 103c, whereby the drive ring 103 is rotationally driven.

[0017] In this embodiment, the rotational force of the driving portion 101 is transmitted from the pinion 104 to the drive ring 103 via the intermediate gear 107, but the rotational force may be transmitted directly without using an intermediate gear, or a drive lever may be used instead of the pinion. When using a drive lever, the driven portion of the drive ring 103 is composed of a cam groove or a driven pin, etc.

[0018] In the meshing between the driven portion 103c of the drive ring 103 and the intermediate gear 107, the amount of meshing is minimized and the meshing area is reduced, resulting in less noise from the gears meshing together. Furthermore, because there is a large mass difference between the pinion 104 and the drive ring 103, even if there is backlash between the pinion 104 and the driven portion 103c, the noise from the gears meshing and reversing is reduced.

[0019] Furthermore, the base 103a of the drive ring 103 has a substantially uniform thickness and is free from unnecessary bumps or holes, thus preventing malfunctions such as the aperture blades 105 getting caught on the drive ring 103 during opening and closing operations.

[0020] Furthermore, as shown in Figure 3A and its cross-sectional view Figure 3B, the drive ring 103 has a first engaging ring 103d and a second engaging ring 103e. The first engaging ring 103d and the second engaging ring 103e form a cylindrical portion 103g. The first engaging ring 103d and the second engaging ring 103e engage with the first engaging projection 102a and the second engaging projection 102b of the holding substrate 102, thereby allowing the drive ring 103 to be rotatably held relative to the holding substrate 102. In addition, the first engaging ring 103d of the drive ring 103 has a larger outer diameter than the second engaging ring 103e.

[0021] In this embodiment, an engaging projection is formed on the retaining substrate 102 and an engaging ring is formed on the driving ring 103. However, it is also possible to form an engaging ring on the retaining substrate 102 and an engaging projection on the driving ring 103.

[0022] Furthermore, a cam groove 103b is formed in the drive ring 103. This cam groove 103b engages with the cam pin 105b of the aperture blade 105. As a result, the aperture blade 105 moves in and out of the light path as the drive ring 103 rotates.

[0023] Next, the positional relationship between the cam groove 103b and the engaging ring 103d of the drive ring 103 will be explained using Figure 3C. As mentioned above, the first engaging ring 103d of the drive ring 103 is provided so as to slide against the first engaging projection 102a of the retaining substrate 102, but these sliding contact portions are set to be offset from the cam groove 103b in the direction of light passage. By doing so, the cam groove 103b and the engaging ring 103d can be set to overlap radially when viewed in the direction of light passage. In other words, the diameter of the engaging ring 103d can be reduced, resulting in a structure that is advantageous for miniaturization.

[0024] Furthermore, as shown in Figure 3C, by setting the driven portion 103c and the engaging ring 103d to overlap radially when viewed in the direction of light passage, the expansion of the outer shape of the drive ring 103 can be suppressed, resulting in a structure that is advantageous for miniaturization.

[0025] Here, we will explain in more detail the configuration in which the holding substrate 102 rotatably holds the drive ring 103.

[0026] As shown in Figure 4, the sliding contact portion between the first engaging projection 102a of the retaining substrate 102 and the first engaging ring 103d of the drive ring 103 is designated as the first sliding contact portion, and the sliding contact portion between the second engaging projection 102b of the retaining substrate and the second engaging ring 103e of the drive ring 103 is designated as the second sliding contact portion. In this embodiment, the diameter of the second sliding contact portion is set to be smaller than that of the first sliding contact portion. As a result, as shown in Figure 5, when assembling the drive ring 103 into the retaining substrate 102, the second engaging ring 103e of the drive ring 103 and the first engaging projection 102a of the retaining substrate 102 are less likely to come into contact, allowing for smooth assembly while preventing scratches and dents. In other words, in a structure having two or more sliding contact portions, it is preferable to set the diameter of the sliding contact portion on the front side in the assembly direction to be smaller than the diameter of the sliding contact portion on the rear side in the assembly direction.

[0027] In this embodiment, an engaging ring is provided on the drive ring 103 and an engaging projection is provided on the holding substrate 102, but the same effect can be obtained even if the relationship is reversed. Furthermore, in this embodiment, there are two sliding contact points, but the same effect can be obtained even with three or more points by configuring the relationship between the diameters of the sliding contact points in the same way.

[0028] Furthermore, in this embodiment, as shown in Figure 2, the first engaging projection 102a and the second engaging projection 102b of the holding substrate 102 are arranged with a phase difference in the circumferential direction. This makes it possible to create a mold structure in which both engaging projections are formed on either the movable side mold or the fixed side mold for molding the holding substrate 102. By doing so, the relative coaxiality of both engaging projections is maintained, and the drive ring 103 can be held rotatably with high precision.

[0029] Figure 6 is a perspective view of the aperture blade 105. A drive hole 105a and a cam pin 105b are provided on the blade portion 105c. The aperture blade 105 can be manufactured by, for example, resin molding, with the blade portion 105c, drive hole 105a, and cam pin 105b integrated into one piece. Alternatively, it may be manufactured by press-forming a PET sheet material or by resin molding.

[0030] Furthermore, although this embodiment uses six aperture blades 105, the number of aperture blades 105 can be any number of two or more. In this embodiment, aperture blades 105 have been used as an example, but other shutter blades or blades with optical filters, or other blade configurations suitable for various applications, may be used. The maximum opening of the portion through which light passes may be defined by the opening of the opening forming member 106 or the holding substrate 102, or by the inner diameter of the multiple aperture blades 105.

[0031] Alternatively, the blade portion 105c may be made from a light-shielding sheet material, and the cam pin 105b may be made by resin molding and integrated with the blade portion 105c by bonding, welding, or insert molding. Alternatively, the cam pin 105b may be formed from a metal pin and integrated with the blade portion 105c by bonding, welding, or crimping.

[0032] Furthermore, in this embodiment, a drive hole 105a is provided in the aperture blade 105 and an engagement pin 102c is provided in the retaining substrate 102. However, a structure in which the drive pin is provided in the aperture blade 105 and the engagement hole is provided in the retaining substrate 102 may also be used.

[0033] In this way, the drive hole 105a, which serves as the rotational axis of the aperture blade 105, engages with the engagement pin 102c of the retaining substrate 102. Also, the cam pin 105b of the aperture blade 105 engages with the cam groove 103b of the drive ring 103. When the pinion 104 rotates, driving force is transmitted to the driven part 103c of the drive ring 103, causing the drive ring 103 to rotate. As the drive ring 103 rotates, driving force is transmitted from the cam groove 103b of the drive ring 103 to the cam pin 105b of the aperture blade 105, driving the aperture blade 105. The cam groove 103b allows the aperture blade 105 to move in and out of the opening of the retaining substrate 102. Multiple aperture blades 105 allow the aperture shape to be adjusted, making it possible to adjust the amount of light that passes through.

[0034] Figure 7 is a perspective view of the opening-forming member 106. The opening-forming member 106 has a hole 106a formed therein, which fits onto the tip of the engagement pin 102c of the retaining substrate 102 and holds down the aperture blade 105.

[0035] <Embodiment 2> Figure 8 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 Embodiment 1, and the camera body to which the interchangeable lens is attached.

[0036] The barrel of the interchangeable lens 221 houses a photographic optical system including a variable magnification lens 232, an aperture device 100 of a first or second embodiment for narrowing the optical path, and a focusing lens 229.

[0037] 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.

[0038] 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.

[0039] 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).

[0040] Furthermore, the controller 222 controls the drive unit 101 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.

[0041] 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]

[0042] 101 Drive unit 102 Holding board 103 Drive Ring 104 pinion 105 aperture blades 106 Opening forming member 107 Intermediate gear

Claims

1. A base member having an opening that allows light to pass through, A group of aperture blades that narrows the aforementioned opening, A drive ring is provided with a cam groove and drives the aperture blade group that engages via the cam groove, The drive unit transmits driving force to the drive ring via a gear provided on the drive ring, The drive ring has a cylindrical portion between the gear and the cam groove, A light intensity adjustment device characterized in that the gear and the cylindrical portion overlap in the direction of light passage.

2. The light intensity adjustment device according to claim 1, characterized in that the base member has a second cylindrical portion provided with a first sliding contact portion that slides against the cylindrical portion.

3. The light intensity adjustment device according to claim 2, characterized in that the base member has a second sliding contact portion different from the first sliding contact portion at a position in a different direction of light transmission.

4. The light intensity adjustment device according to claim 3, characterized in that the drive ring has a first engaging ring that slides with the first sliding contact portion and a second engaging ring that slides with the second sliding contact portion on the cylindrical portion.

5. The light intensity adjustment device according to claim 4, characterized in that the second engaging ring is positioned further away from the cam groove in the light transmission direction than the first engaging ring, and the diameter of the second engaging ring is smaller than the diameter of the first engaging ring.

6. The light intensity adjustment device according to claim 1, characterized in that the cam groove and the cylindrical portion overlap in the direction of light passage.

7. A light intensity control device according to any one of claims 1 to 6, An image sensor that captures light that has passed through the light intensity adjustment device, An imaging device characterized by comprising:

Images