JP2014164049A - Light quantity adjusting device and optical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light quantity adjusting device capable of being downsized, and to provide an optical apparatus equipped with the light quantity adjusting device and a lens.SOLUTION: A light quantity adjusting device 10 changes the size of a light passage opening using a plurality of light quantity adjusting blades 31-36. The plurality of light quantity adjusting blades 31-36 include blades 31b-36b for forming the light passage opening and bases 31a-36a having thicknesses thicker than those of the blades 31b-36b, and forms the light passage opening by overlapping only adjacent blades in a circular pattern, with a first shaft serving as a rotary shaft provided on the bases 31a-36a as a supporting point.

Description

  The present invention relates to a light amount adjusting device used in an optical apparatus such as a digital still camera.

  Cameras and interchangeable lenses are provided with an aperture device (light amount adjusting device) that can change the aperture diameter to adjust the amount of light reaching the imaging surface of the image sensor or film, and the depth of field. It has been. In many cases, a similar light amount adjusting device is also provided in a projection optical system of a projector that projects light from an image modulation element such as a liquid crystal panel. Such a light quantity adjusting device includes a so-called iris diaphragm in which a plurality of (three or more) diaphragm blades are rotated to change the aperture diameter like an iris. A shaft portion and a hole portion serving as a driven central portion and a driven portion that receives a driving force are formed at the base portion of each diaphragm blade used for the iris diaphragm. In addition, an aperture for allowing light to pass is formed by a blade portion of each diaphragm blade that is distant from each shaft portion from the base portion overlapping another diaphragm blade in the optical axis direction. Among the manufacturing methods of the diaphragm blades, a method is disclosed in which the base portion is formed thicker than the blade portions. (Patent Document 1)

Japanese Patent No. 5028105

  However, in patent document 1, the base part and blade | wing part which are thicker than the blade | wing part of an aperture blade are piled up. For this reason, it is difficult to reduce the thickness of the light amount adjusting device, and an imaging device (for example, a camera) on which the light amount adjusting device is mounted is also increased in size.

  The present invention provides a light amount adjusting device and an optical apparatus that can be reduced in size in the optical axis direction.

  In order to solve the above problems, a light amount adjusting device of the present invention is a light amount adjusting device that changes the size of a light passage opening by a plurality of light amount adjustment blades, wherein the plurality of light amount adjustment blades are the light passage openings. The light passage opening is formed by overlapping only the adjacent blade portions in a ring shape with a pivot shaft provided on the base portion as a fulcrum. It is characterized by doing. Moreover, in order to solve the said subject, the optical apparatus of this invention is provided with the optical system by which a light quantity is adjusted with this light quantity adjustment apparatus.

  According to the present invention, the light quantity adjusting device can be downsized in the optical axis direction.

1 is an exploded perspective view showing a main part of a light amount adjusting apparatus according to Embodiment 1 of the present invention. The disassembled perspective view which shows the main part back side used for the light quantity adjustment apparatus of Example 1. FIG. The top view of the aperture blade used for the light quantity adjustment apparatus of Example 1 Side view of the diaphragm blades of the light amount adjusting device of Embodiment 1 The figure which looked at the aperture blade in the open state of the light quantity adjustment apparatus of Example 1 from the optical axis direction The figure which looked at the stop blade in the middle stop state of the light quantity adjusting device of Example 1 from the optical axis direction The figure which looked at the aperture blade in the small aperture state of the light quantity adjustment apparatus of Example 1 from the optical axis direction Assembly external view of the light quantity adjusting device of Example 1 FIG. 2 is a schematic diagram of an optical apparatus in which the aperture device of Embodiment 1 is mounted.

  Embodiments of the present invention will be described below with reference to the drawings.

Example 1
8 is mounted on an optical system of an optical device such as a camera, and adjusts the amount of light that enters from an object (not shown) and reaches the image sensor by changing a diaphragm aperture diameter described later. .

  FIG. 1 shows an exploded view of the light amount adjusting device 10, and FIG. 2 shows the back side of FIG. 3 and 4 are a plan view and a side view of one of the diaphragm blades used in each light quantity adjusting device 10, respectively.

  The base plate 1 in FIG. 1 is a component for mounting components such as a rotating member 2, light amount adjusting blades 31 to 36, a suppressing member 4, and a stepping motor 6 described later. Reference numerals 1a to f denote shaft holes for inserting 31c to 36c formed in diaphragm blades 31 to 36 of light quantity adjusting blades to be described later, 1g denotes a through hole into which a stepping motor 6 to be described later is inserted, and 1h to 1l. Is a protrusion on which 2g formed by the rotating member 2 is slid.

  In FIG. 1, reference numerals 31, 32, 33, 34, 35, and 36 denote diaphragm blades as light quantity adjustment blades. These diaphragm blades 31 to 36 are thin plate-like integrally molded parts made of synthetic resin. Each diaphragm blade includes base portions 31a, 32a, 33a, 34a, 35a, and 36a, and blade portions 31b, 32b, 33b, 34b, 35b, and 36b having a thickness smaller than that of the base portion. By performing integral molding with a synthetic resin, it is possible to use a light quantity adjusting blade with high productivity and high dimensional accuracy.

  First shaft portions 31c, 32c, 33c, 34c, 35c, and 36c having an axial shape are formed on the surfaces of the base portions 31a to 36a so as to be the rotation centers of the diaphragm blades 31 to 36, respectively. In addition, second shaft portions 31d, 32d, 33d, 34d, 35d, and 36d having an axial shape are formed so as to be driven portions to which a driving force is input in the respective diaphragm blades 31 to 36.

  Reference numeral 2 denotes a ring-shaped rotating member, and an opening 2j is formed at the center thereof. The rotating member 2 is formed with cam groove portions 2a, 2b, 2c, 2d, 2e, and 2f for driving the driven portions 31d to 36d. The outer peripheral portion 2g is formed on the base plate 1. 1h, 1i, 1j, 1k, 1l. A part of the rotating member 2 in the circumferential direction has a gear portion 2h.

  Reference numeral 4 denotes a pressing member. An opening 4 a is formed at the center of the pressing member, and the diaphragm blades 31 to 36 and the rotating member 2 are provided so as not to be detached from the main plate 1.

  A stepping motor 6 drives the rotating member 2, and a pinion gear 5 is attached to the output shaft of the stepping motor 6. The stepping motor 6 is fitted to the motor mounting portion 1g of the base plate 1 and is screwed with screws 7. The pinion gear 5 passes through the hole 1g of the base plate 1 and meshes with the gear portion 2h of the rotating member 2. The base plate 1, the rotating member 2, the pinion gear 5, and the stepping motor 6 constitute a drive mechanism.

  The presser member 4 is fixed to the base plate 1 with the diaphragm blades 31 to 36 sandwiched between the rotary member 2 and plays a role of preventing the rotary member 2 and the diaphragm blades 31 to 36 from coming off in the optical axis direction (light passage direction). . The outer peripheral portion 2h of the rotating member 2 is received by protrusions 1h, 1i, 1j, 1k, and 1l provided in the circumferential direction of the main plate 1, and is rotatably inserted. The outer peripheral part 2g of the rotating member 2 is rotatably supported by sliding with the projecting parts 1h, 1i, 1j, 1k, 1l of the base plate 1. The first shaft portions 31c to 36c of the aperture blades 31 to 36 are rotatably inserted into shaft hole portions 1a to 1f formed in the base plate 1, respectively. Further, the second shaft portions 31d to 36d are inserted into cam groove portions 2a, 2b, 2c, 2d, 2e, and 2f formed in the rotary member 2, respectively.

  When the stepping motor 6 fixed to the main plate 1 operates and the pinion gear 5 rotates, the rotating member 2 in which the gear portion 2h is engaged with the pinion gear 5 rotates. Thereby, each diaphragm blade moves the second shaft portion along the cam groove portion of the rotating member 2 (that is, the second shaft portion receives a driving force from the cam groove portion), and rotates around the first shaft portion.

  The diaphragm blades 31 to 36 are arranged at equiangular intervals around the optical axis (the center position of the openings 2j and 4a). Although details will be described later, the diaphragm blades 31 to 36 are partially overlapped with each other. A diaphragm aperture which is a light passage aperture is formed inside the aperture. Then, as the diaphragm blades 31 to 36 rotate, their overlapping amounts change and the size (size) of the aperture opening changes continuously. The larger the overlap amount of the diaphragm blades 31 to 36, the smaller the size of the diaphragm aperture.

Here, as shown in FIG. 4, in the present embodiment, the thickness t2 of the blade portion 31b is set to ½ or less of the thickness t1 of the base portion 31a. However, this is an example, and it is only necessary to satisfy the relationship of t1> t2. That is, in the open state, when there is an intermediate aperture state where t1> 2 × t2 is satisfied and three blades overlap, it is more preferable that t1> 3 × t2. This is because the light amount adjusting device is advantageous for downsizing in the optical axis direction.

  Also, as shown in FIG. 4, tapered surfaces (inclined surfaces) 31e and 31f are provided at the tips of the first shaft portion 31c and the second shaft portion 31d, respectively. Thereby, sliding resistance with the shaft hole part 1a of the base plate 1 and the cam groove 2a of the rotating member 2 can be lowered. In addition, base side surface portions 31k to 36k are provided as the surfaces of the step portions between the base portions 31a to 36a and the blade portions 31b to 36b of the diaphragm blades 31 to 36, respectively. As portions of the blade portions 31b to 36b that contact the base portion side surface portions 31k to 36k, blade portion side surface portions 31j to 36j are provided.

  In addition, curved surfaces (may be tapered surfaces) 31g and 31h are provided at the bases of the first shaft portion 31c and the second shaft portion 31d, respectively, thereby reducing the flow resistance and release resistance of the resin during injection molding. The diaphragm blades 31 can be formed more stably by lowering, and the strength of each shaft portion can be improved.

  A tapered surface (which may be a curved surface) 31 i inclined with respect to the thickness direction is formed on the outer peripheral edge of the diaphragm blade 31. The tapered surface 31i prevents the light impinging on the outer peripheral edge of the diaphragm blade 31 from being irregularly reflected to generate unnecessary light such as a ghost, and also prevents the diaphragm blades 31 to 36 from being caught when they overlap. It also has a role of reducing the operating resistance.

  5 to 7 show respective states when the operation states of the diaphragm blades 1 to 6 in the light amount adjusting device 10 are viewed from the optical axis direction. FIG. 5 shows the state of the aperture opening diameter below, FIG. 5 shows the state where the aperture opening diameter of the light amount adjusting device 10 is open, FIG. 6 shows the intermediate stop state of the light amount adjusting device, and FIG. In the present invention, the open state means a state in which the aperture diameter of the light passage opening formed by the diaphragm blades is maximum (that is, the fully opened state), and the diaphragm blades project into the opening 4 a of the pressing member 4 at the opening of the base plate 1. Instead, it may be located only between the main plate 1 and the presser member 4. The maximum opening diameter may be determined by the cam grooves 2a to 2f, or the position of the diaphragm blade may be determined by other grooves, protrusions, or steps. In any of the open state, the intermediate stop state, and the small stop state, the stop blades 31 to 36 partially overlap each other. That is, if the gap between the driving member 2 and the pressing member 4 is determined as the thickness of the thick base portions 31a to 36a, the influence of the dimensional tolerance of the blade portions 32b to 36b can be reduced and the assembly can be performed accurately.

  In the open state of FIG. 5, when focusing on the diaphragm blade 32 adjacent to the diaphragm blade 31 in the clockwise direction, the blade portion 31b of the diaphragm blade 31 (the tip side of the blade portion 31b) and the blade portion 32b of the diaphragm blade 32 ( The base portion side of the blade portion 32b close to the base portion 32a is annularly overlapped, and the side surface portion 31j of the blade portion 31b of the diaphragm blade 31 is in contact with the side surface portion 32k of the base portion 32a of the diaphragm blade 32. The state is fully open. When attention is paid to the diaphragm blade 31 and the diaphragm blade 36 adjacent in the counterclockwise direction, the blade portion 31b of the diaphragm blade 31 and the blade portion 36b of the diaphragm blade 36 overlap in an annular shape, and the base of the diaphragm blade 31 The base side surface portion 31k of 31a is in contact with the blade portion side surface portion 36j of the blade portion 36b of the aperture blade 36, and the fully open state is defined by this contact state. In this open state, the light passage opening is formed only by the blade portions 31b-36b of the diaphragm blades 31-36. That is, the blade portions 31b to 36b are relatively thinner than the base portions 31b to 36b from the end portions on the base portions 31a to 36a side to the blade tip portion side, and the adjacent blade portions 31b to 36b are base portions from the blade tip portion side to the base portion. It overlaps each other over the side.

  As described above, in the present embodiment, the plurality of light quantity adjustment blades 31 to 36 include the blade portions 31b to 36b that form the light passage openings and the base portions 31a to 36a that are thicker than the blade portions 31b to 36b, and the base portion 31a. With the first shaft portions 31c to 36c serving as the rotation shafts provided on the 36a to 36a as fulcrums, only the adjacent blade portions 31b to 36b are annularly overlapped to form a light passage opening. That is, a difference is provided in the thicknesses of the base portions 31a to 36a and the blade portions 31b to 36b, and only the adjacent thin blade portions 31b to 36b are overlapped in an annular manner to form a light passage opening only by the blade portions 31b to 36b. Thus, the light quantity adjusting device can be downsized in the optical axis direction.

  Further, the blade portion side surface portions 31k to 36k that are the end portions (outer end portions) opposite to the light passing opening side ends (inner end portions) of the blade portions 31b to 36b that form the blade tip portions, It abuts on the base portions 31a to 36a of the adjacent light quantity adjustment blades 31 to 36. Thus, the base parts 31a to 36a and the blade parts 31b to 36b are not sandwiched between the base plate 1, the rotating member 2 and the restraining member 4 which are case members for unitizing the light quantity adjusting blades 31 to 36, and the parts. Even if there is an original dimensional tolerance or a backlash generated between parts, the opening diameter can be determined stably.

  Furthermore, when moving from the intermediate aperture state or the small aperture state to the open state, the ridge line of the blade portion 31b having the same shape and the ridge line of the base side surface portion 32k come into contact with each other. That is, the outer end portions of the blade portions 31b to 36b on the blade tip portion side are in linear contact with the base portions 31a to 36a. In this way, the plurality of adjacent light quantity adjustment blades 31 to 36 are substantially decelerated by abutting linearly with each other, and further, the blade portion 31b of the diaphragm blade can be prevented from being lifted to the base portion 32a. it can. In this embodiment, the ridge line shape of the blade part 31b and the ridge line shape of the base side surface part 32k are formed in a straight line so as to be excellent in productivity, but an inflection point is provided to increase the contact area. Can also make it easier to slow down.

  Further, in the intermediate aperture state of FIG. 6 and the small aperture state of FIG. 7 (a state where the aperture is smaller than the specific aperture diameter), the overlap of the aperture blades 31 to 36 is as follows.

  Focusing on the diaphragm blade 31 and the diaphragm blade 32, a part of the blade part 31b of the diaphragm blade 31 overlaps with a part of the blade part 32b of the diaphragm blade 32, and the base parts of each other or the blade part and the base part do not overlap. Further, the other surface of the blade portion 31b overlaps with a part of the blade portion 36b, and the blade portions 31b to 36b are alternately arranged along the circumferential direction, so that these intermediate diaphragm state and small diaphragm state Then, the aperture opening is formed by the blade portions 31b to 36b among the aperture blades 31 to 36. That is, the aperture opening is not formed by the thick base portions 31a to 36a, and is formed only by the thin blade portions 31b to 36b.

  As described above, in all operating states including the open state, the intermediate stop state, and the small stop state, the first and second shaft portions provided with the two stop blades that are stopped together are thicker than the base portions or the base portions. Thin blades and bases do not overlap. Thereby, the optical axis direction dimension of the storage space of the diaphragm blades 31 to 36 between the rotating member 2 and the pressing member 4 can be thinned, and the optical axis direction dimension (thickness) of the light amount adjusting device 10 can be reduced. Can do. At this time, the blade portion 31b rotates on the optical axis side in a direction orthogonal to the optical axis with respect to the first shaft portion 32c and the second shaft portion 32d of another adjacent diaphragm blade 32.

  Further, when the base side surface portions 31k to 36k are formed in a linear shape, the parallel relationship is maintained until the blade portion side surface portions 31j to 36j of the opposed blade portions 31b to 36b change from the open state to the small aperture state. . Further, even in the open state, since the blade portions thinner than the base portion overlap each other, the amount of warping of the blade portion is smaller than when the blade portion overlaps the base portion.

  In addition, since the aperture opening is formed only by the blade portions 31b to 36b in the small aperture state, a step in the optical axis direction between the aperture opening surface and the blade portions 31b to 36b surrounding the periphery is reduced. Therefore, it is possible to make it difficult to generate diffraction at the time of a small aperture, which is more likely to occur as the level difference is larger, and as a result, it is possible to reduce deterioration in optical performance.

In the above-described embodiment, the light quantity adjusting device having six diaphragm blades has been described. However, the number of diaphragm blades may be a plurality other than six, and the diaphragm blades are rotated by a driving method without using a rotating member. May be.

  In the above embodiment, the light amount adjusting device in which the light passage opening is formed at substantially the same position in the direction orthogonal to the optical axis is shown. However, the curved surface shape is rotated by using a rotating member having a convex shape on one side in the optical axis direction. A moving light amount adjusting blade may be used. When rotating the curved surface shape, the rotation axis of the light quantity adjusting blade has a predetermined angle with respect to the optical axis. It is preferable that the sphere center of each axis is located in the axial direction of the rotation axis of the plurality of light quantity adjusting blades.

In the above embodiment, the light amount adjusting device mounted on the imaging optical device has been described. However, the same light amount adjusting device as that in the above embodiment may be mounted on an optical device other than the imaging device such as a projector.

(Example 2)
FIG. 9 shows a schematic configuration of a video camera (imaging device) as an optical apparatus equipped with the diaphragm device described in the first embodiment.

  Reference numeral 21 denotes a lens barrel of the video camera. In the lens barrel portion 21, a photographic optical system including the variable magnification lens 23, the diaphragm device 20 of the first embodiment, and the focus lens 29 is accommodated.

  Reference numeral 25 denotes an image sensor composed of photoelectric conversion elements such as a CCD sensor and a CMOS sensor. The image sensor 25 photoelectrically converts a subject image formed by the photographing optical system and outputs an electrical signal. The brightness of the subject image formed on the image sensor 25 (that is, the amount of light reaching the image sensor 25) is appropriately set by changing the aperture of the aperture device 20 or moving the ND filter back and forth. Can do.

  The electrical signal output from the image sensor 25 is subjected to various image processing by the image processing circuit 26. Thereby, a video signal (video output) is generated.

  The controller 22 controls the zoom motor 24 in response to an operation of a zoom switch (not shown) by the user, and moves the zoom lens 23 to perform zooming. The controller 22 detects the contrast of the video signal, controls the focus motor 28 according to the contrast, and moves the focus lens 29 to perform autofocus.

  Further, the controller 22 controls the diaphragm drive unit 6 of the diaphragm device 20 based on the luminance information in the video signal to adjust the light amount. Thereby, blur and ghost at the time of shooting can be made into a natural shape, and high-quality video can be recorded. In addition, since the aperture device 20 incorporated in the lens barrel portion is small, the lens barrel portion and the entire video camera can be miniaturized.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

DESCRIPTION OF SYMBOLS 1 Ground plate 2 Rotating member 3 Light quantity adjustment blade | wing 31a, 32a, 33a, 34a, 35a, 36a Base part 31b, 32b, 33b, 34b, 35b, 36b Blade | wing part 31c, 32c, 33c, 34c, 35c, 36c 1st axis | shaft 31d, 32d, 33d, 34d, 35d, 36d Second shaft 31g, 32g, 33g, 34g, 35g, 36g Curved surface 31h, 32h, 33h, 34h, 35h, 36h Curved surface 31j, 32j, 33j, 34j, 35j, 36j Blade side surface Part 31k, 32k, 33k, 34k, 35k, 36k Base side surface part t1 Blade part thickness t2 Base part thickness 10, 20 Light quantity adjusting device

Claims (8)

A light amount adjusting device that changes the size of the light passage opening by a plurality of light amount adjusting blades,
The plurality of light quantity adjustment blades include a blade portion that forms the light passage opening and a base portion that is thicker than the blade portion, and the adjacent blade portions that are adjacent to each other with a rotation shaft provided on the base portion as a fulcrum. A light amount adjusting device characterized in that the light passage opening is formed by superimposing only a ring shape. The thickness of the blade portion is provided relatively thinner than the base portion from the portion corresponding to the base side to the blade tip side,
The light quantity adjusting device according to claim 1, wherein the adjacent blade portions overlap each other from the blade tip portion side to the base portion side.   The light quantity according to claim 1 or 2, wherein the size of the light passage opening is changed by changing the overlapping state of the blade parts by rotation of the plurality of light quantity adjustment blades arranged in a ring shape. Adjusting device.   The plurality of light amount adjustment blades are configured such that an outer end opposite to an inner end forming the light passage opening of the blade tip portion serving as the blade portion is brought into contact with an end portion of the adjacent base portion. The light amount adjusting device according to claim 3, wherein a full opening state of the passage opening is formed.   The light quantity adjusting device according to claim 4, wherein the outer end portion of the blade tip portion and the adjacent base portion are in linear contact with each other.   The light quantity adjusting device according to any one of claims 1 to 5, wherein the plurality of light quantity adjusting blades have an inclined surface provided at a stepped portion from the base portion to the blade portion.   The light quantity adjusting device according to any one of claims 1 to 6, wherein a thickness of the blade portion is equal to or less than half of a thickness of the base portion.   An optical device comprising the light amount adjusting device according to claim 1 in an optical system.

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