JP2010102044A - Light quantity adjusting device, lens barrel, and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent diffraction reduction due to small narrowing by a plurality of dimmer filters, and to reduce size even using the plurality of dimmer filters. <P>SOLUTION: A light quantity adjusting device includes an upper diaphragm blade 41 and lower diaphragm blade 44 capable of reciprocating between a full open position for fully opening an aperture 31a and a narrowing position for narrowing the opening amount of the aperture 31a, a diaphragm driving motor 51 for increasing and decreasing the opening amount of the diaphragm aperture formed on the surface side of the aperture 31a by the upper diaphragm blade 41 and lower diaphragm blade 44, an upper ND filter 67 and lower ND filter 68 capable of reciprocating between an evacuating position separated from the diaphragm aperture and a shielding position for covering the all of the diaphragm aperture and reducing the light quantity passing through the diaphragm aperture, and an ND driving motor 71 for switching the state where the upper ND filter 67 and lower ND filter 68 are at the evacuating position, the state where only the lower ND filter 68 is at the shielding position, and the state where the upper ND filter 67 and lower ND filter 68 are at the shielding position. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light amount adjusting device, a lens barrel, and an imaging device having a plurality of independent diaphragm blades and a plurality of independent neutral density filters. More specifically, the present invention relates to a technique for preventing a diffraction phenomenon caused by a small stop by using a plurality of neutral density filters and reducing the size even if a plurality of neutral density filters are used.

  2. Description of the Related Art Conventionally, an imaging apparatus such as a digital still camera or a digital video camera forms a subject image with a plurality of lenses arranged in a state where optical axes coincide with a lens barrel body. The subject image is received by an image pickup device such as a charge coupled device image sensor (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor, photoelectrically converted, and output as an electric signal. Therefore, digital image data corresponding to the subject image is generated.

  Here, when shooting a bright subject, the amount of light is reduced by a light amount adjustment device having a plurality of aperture blades in order to reduce the amount of light incident on the image sensor. In this case, for example, if the aperture amount of the aperture opening formed by each aperture blade is reduced to the pinhole state, a diffraction phenomenon occurs and a so-called small aperture state is obtained. Therefore, there is a problem that a good image cannot be obtained.

Therefore, the drive means drives a plurality of light quantity adjustment members (diaphragm blades) to change the aperture diameter of the aperture opening, and the drive means puts in and out of the effective light beam in a plane substantially perpendicular to the optical axis. 2. Description of the Related Art A light amount adjusting device having a possible ND filter (a neutral density filter) is known. The ND filter has a plurality of regions having different transmittances, and when entering from the outside of the effective ray into the effective ray, the region having a high transmittance enters the effective ray first. For this reason, when the light transmittance is insufficient in a region with high transmittance, the dynamic range of exposure control can be widened by placing the region with low transmittance in the effective light beam (see, for example, Patent Document 1).
JP 2000-214514 A

A ground plate having an exposure opening (aperture aperture); a slide member slidably supported on the ground plate; and a light amount attenuating filter attached to the slide member to advance and retract to the exposure opening to reduce the light amount. There is known a light amount adjusting device provided with the above. Specifically, the light quantity attenuation filter is composed of a plurality of light attenuation filters stacked on a slide member, and slides such that the largest filter among the plurality of light attenuation filters is located outside. Affixed to the member. Therefore, the amount of incident light to the image sensor can be reduced by sliding the light amount reducing filter to the exposure opening without reducing the opening amount to the pinhole state (see, for example, Patent Document 2).
JP 2002-357857 A

  However, the technique disclosed in Patent Document 1 uses one ND filter (a neutral density filter) having a plurality of regions having different transmittances. Therefore, the ND filter becomes larger than the case where the transmittance is only one, and as a result, there is a problem that the light amount adjusting device is enlarged.

  On the other hand, the technique of Patent Document 2 described above has a plurality of neutral density filters having different sizes. However, since each neutral density filter is affixed to one slide member, each neutral density filter simultaneously advances and retreats in the same direction with respect to the exposure aperture (aperture aperture) to reduce the amount of light. For this reason, a space that allows the largest filter to move is required, and the light amount adjusting device is increased in size.

  Therefore, the problem to be solved by the present invention is to prevent the diffraction phenomenon due to the small aperture by using a plurality of neutral density filters and to reduce the size even if a plurality of neutral density filters are used.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, an opening for allowing light to enter is formed, and a ground plane disposed in a direction perpendicular to the optical axis of incident light from the opening, and the ground plane A plurality of independent diaphragm blades mounted along the surface and capable of reciprocating between a fully open position for fully opening the opening and a diaphragm position for restricting the opening amount of the opening; and A diaphragm blade driving means that moves and increases or decreases the aperture amount of the diaphragm opening formed on the surface side of the opening by each diaphragm blade, and a retracted position that is attached along the surface of the base plate and separated from the diaphragm opening And a plurality of independent neutral density filters capable of increasing and decreasing the amount of light passing through the aperture opening by reciprocating between the shielding position covering all the aperture apertures, and moving each of the neutral density filters, Of the dimming A dimming filter driving means for switching between a state in which the filter is in the retracted position, a state in which only some of the neutral density filters are in the shielding position, and a state in which all the neutral density filters are in the shielding position. is there.

  According to a seventh aspect of the present invention, there is provided an imaging lens, a lens barrel body that houses the lens, and an opening for allowing light from the lens to enter. A ground plane disposed in a direction perpendicular to the optical axis of the incident light, a fully open position that is attached along the surface of the ground plane and that fully opens the opening, and a diaphragm position that restricts an opening amount of the opening. A plurality of independent diaphragm blades that can reciprocate between the diaphragm blades, and the diaphragm blades that move the diaphragm blades to increase or decrease the aperture amount of the diaphragm aperture formed on the surface side of the opening by the diaphragm blades. Increasing or decreasing the amount of light passing through the aperture opening by reciprocating between a driving means and a retracted position away from the aperture opening and a shielding position covering all the aperture apertures, attached along the surface of the base plate Multiple possible A standing neutral density filter, each neutral density filter being moved, a state in which all the neutral density filters are in a retracted position, a state in which only some of the neutral density filters are in a shielding position, and a total of the neutral density filters It is a lens barrel having a neutral density filter driving means for switching the state where the filter is in the shielding position.

  Furthermore, according to an eighth aspect of the present invention, there is provided an imaging lens, a lens barrel main body that accommodates the lens, and an opening for allowing light from the lens to enter the opening. A ground plane disposed in a direction perpendicular to the optical axis of the incident light from, an imaging device disposed on the optical axis behind the ground plane in the incident direction, and attached along the surface of the ground plane, A plurality of independent aperture blades capable of reciprocating between a fully open position for fully opening the aperture and an aperture position for reducing the aperture amount of the aperture, and moving each aperture blade, A diaphragm blade driving means for increasing / decreasing the aperture amount of the aperture opening formed on the surface side of the aperture, and a shield that is attached along the surface of the main plate and covers all of the aperture position and the retracted position away from the aperture opening Round trip between locations A plurality of independent neutral density filters capable of moving to increase or decrease the amount of light passing through the aperture, and moving each neutral density filter, all the neutral density filters being in the retracted position, partly And a neutral density filter driving means for switching between a state where only the neutral density filter is in the shielding position and a status where all the neutral density filters are in the shielding position.

(Function)
In the first, seventh, and eighth aspects of the present invention, a plurality of reciprocating motions are possible between a fully open position that fully opens the opening and a throttle position that restricts the opening amount of the opening. Has independent aperture blades. Each diaphragm blade is moved by the diaphragm blade driving means so as to increase or decrease the aperture amount of the aperture opening formed on the surface side of the opening. Therefore, when shooting a bright subject, it is possible to reduce the amount of light by reducing the aperture amount of the aperture opening to reduce the amount of light incident on the image sensor.

  In the first, seventh, and eighth aspects of the present invention, the reciprocating movement between the retracted position away from the diaphragm opening and the shielding position covering all the diaphragm openings passes through the diaphragm opening. It has a plurality of independent neutral density filters that can increase or decrease the amount of light. And this neutral density filter can be moved to the state in a shielding position by the neutral density filter drive means. Therefore, the amount of light can be adjusted by moving the neutral density filter to the shielding position without reducing the aperture amount of the aperture opening to the pinhole state.

  Furthermore, a plurality of neutral density filters are provided independently. Then, the neutral density filter driving means switches between a state where all the neutral density filters are at the retracted position, a state where only some neutral density filters are at the shield position, and a state where all the neutral density filters are at the shield position. Therefore, it is possible to reduce the size of the neutral density filter as compared with a case where a single neutral density filter having a plurality of regions having different transmittances is used (the technique of Patent Document 1). Further, the moving space of the neutral density filter can be reduced as compared with a case where a plurality of neutral density filters are simultaneously advanced and retracted in the same direction (the technique of Patent Document 2).

  According to the invention described above, the amount of light can be adjusted by moving the neutral density filter to the shielding position without reducing the aperture amount of the aperture opening to the pinhole state, so that the diffraction phenomenon due to the small aperture can be prevented. Further, each of the neutral density filters provided independently can be reduced in size as compared with the case where a single neutral density filter is used. Furthermore, the moving space of the neutral density filter can be made smaller than when a plurality of neutral density filters are simultaneously advanced and retracted in the same direction. Therefore, the light quantity adjusting device can be reduced in size.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below with reference to the drawings.
Here, the imaging device according to the present invention is assumed to be a digital still camera 10 in the following embodiments. In the following embodiments, the lens barrel of the present invention is assumed to be a lens barrel 20 incorporated in the digital still camera 10. The light amount adjusting device 30 (or 80, 90) of the present invention is a part of the lens barrel 20. The description will be given in the following order.

1. First embodiment (light quantity adjusting device 30: an example in which the top of the neutral density filter is small and the bottom is large)
2. Second embodiment (light amount adjusting device 80: an example in which the movements of the upper and lower neutral density filters are changed)
3. Third embodiment (light quantity adjusting device 90: an example in which the top of the neutral density filter is large and the bottom is small)

[External appearance of imaging device]

FIG. 1 is a perspective view showing a digital still camera 10 as an embodiment of an imaging apparatus of the present invention. The digital still camera 10 incorporates a lens barrel 20 as an embodiment of the lens barrel of the present invention. The lens barrel 20 incorporates a light amount adjusting device 30 (or 80, 90) as an embodiment of the light amount adjusting device of the present invention.
As shown in FIG. 1, the digital still camera 10 includes a rectangular parallelepiped case 11 constituting an exterior. A lens barrel 20 indicated by a two-dot chain line in FIG. 1A is incorporated on the right side in the case 11, and the lens 21 provided in the lens barrel 20 is disposed on the front surface of the case 11. Located at the top of the side. In the digital still camera 10 shown in FIG. 1, left and right refer to the left and right viewed from the front side shown in FIG.

  Further, a flash 12 for emitting photographing auxiliary light and an AF (Auto Focus) auxiliary light emitting unit 13 are provided on the left side of the lens 21, and a shutter button 14 is provided on the left side of the upper surface of the case 11. It has been. Further, a cover 11a is provided on the front side of the case 11 so as to be slidable up and down. The cover 11a is located at the lower front side of the case 11 so as to expose the lens 21, the flash 12, and the AF auxiliary light emitting unit 13, and at the upper front side to be a protective position covering the above. Slide between. Therefore, when the cover 11a is set to the shooting position (position shown in FIG. 1A) and the shutter button 14 is pressed, the shooting can be performed.

  Furthermore, on the rear surface of the case 11, a menu button 15, a display 16, a cross key 17, a zoom lever 18, and an exposure correction button 19 are provided. The menu button 15 is used to display various setting menus (still image shooting mode, moving image shooting mode, playback mode, etc.) on the display 16, and the displayed menu is selected with the cross key 17 and pressed with the decision button 17a. Set. The display 16 is, for example, a liquid crystal display, and displays a captured image, reproduces a captured image, and the like in addition to a setting menu. The zoom lever 18 is for zooming the lens barrel 20, and the exposure correction button 19 is for performing exposure correction such as backlight correction with one touch.

[Cross section of lens barrel]

FIG. 2 is a cross-sectional view of the lens barrel 20 in the optical axis direction as an embodiment of the lens barrel of the present invention.
As shown in FIG. 2, the lens barrel 20 includes a front lens group 21a, a zoom lens group 21b, an intermediate lens 21c, and a focus lens group 21d arranged in a state where the optical axis is aligned with the barrel body 20a. This is a 4 group inner focus zoom lens. Therefore, zooming (magnification operation) can be performed by displacing the zoom lens group 21b in the optical axis direction by a stepping motor, a linear motor, or the like. Further, focusing (focus adjustment operation) can be performed by displacing the focus lens group 21d in the optical axis direction. The lens barrel 20 can be used not only for the digital still camera 10 (see FIG. 1) but also for a digital video camera or the like.

  Here, the lens barrel main body 20a is made of a black resin material (for example, polycarbonate resin containing glass fibers) having strength and mass productivity and having light shielding properties. The front lens group 21a and the intermediate lens 21c are fixed to the barrel main body 20a. On the other hand, the zoom lens group 21b is held between the guide shaft 24a and the guide shaft 24b by the zoom lens holding frame 22, and is slidable in the optical axis direction. Further, the focus lens group 21d is held between the guide shaft 24a and the guide shaft 24b by the focus lens holding frame 23, and is slidable in the optical axis direction. The guide shaft 24a and the guide shaft 24b are fixed in parallel with the optical axis inside the barrel main body 20a.

  The lens barrel 20 is provided with a light amount adjusting device 30. The light amount adjusting device 30 is disposed between the intermediate lens 21c and the focus lens group 21d. The diaphragm opening / closing device 40, the diaphragm driving device 50 (corresponding to the diaphragm blade driving means in the present invention), the ND (Neutral Density) filter opening / closing device 60, and the ND filter driving device 70 (the neutral density filter driving means in the present invention). Equivalent). Therefore, by opening and closing the aperture opening / closing device 40 by the aperture driving device 50, the aperture amount of the aperture opening can be increased or decreased. Furthermore, by opening and closing the ND filter opening / closing device 60 by the ND filter driving device 70, the amount of light passing through the aperture opening can be increased or decreased. The ND filter corresponds to the neutral density filter in the present invention, and can reduce the amount of transmitted light.

[Configuration example of imaging device]

FIG. 3 is a block diagram showing a configuration of a digital still camera 10 as an embodiment of the imaging apparatus of the present invention.
As shown in FIG. 3, a lens barrel 20 is incorporated in the digital still camera 10. In addition, a light amount adjusting device 30 is incorporated in the lens barrel 20. Furthermore, the digital still camera 10 includes an image sensor 25, an A / D (Analog / Digital) conversion unit 26, a camera DSP (Digital Signal Processor) 27, a CPU (Central Processing Unit) 28, a memory 29, and a display 16. ing.

  Here, in the lens barrel 20, a front lens group 21a, a zoom lens group 21b, an intermediate lens 21c, and a focus lens group 21d are arranged along the optical axis. A diaphragm opening / closing device 40 constituting a part of the light amount adjusting device 30 is disposed between the intermediate lens 21c and the focus lens group 21d. The aperture opening / closing device 40 is driven by an aperture driving device 50 and can increase or decrease the aperture amount of the aperture opening. For example, when shooting a bright subject, in order to reduce the amount of light incident on the image sensor 25, the amount of aperture is reduced to reduce the amount of light.

  An ND filter opening / closing device 60 that constitutes a part of the light amount adjustment device 30 is also disposed between the intermediate lens 21c and the focus lens group 21d. In the present embodiment, the ND filter opening / closing device 60 is disposed on the incident light side, which is the front side of the aperture opening / closing device 40, and is driven by the ND filter driving device 70. Therefore, by closing the front side of the aperture opening with the ND filter, it is possible to reduce the amount of incident light passing through the aperture opening and prevent the diffraction phenomenon due to the small aperture.

  In the lens barrel 20 in which such a light amount adjusting device 30 is incorporated, incident light (subject image) whose light amount has been adjusted by the ND filter opening / closing device 60 and the diaphragm opening / closing device 40 is imaged on the image sensor 25 and captured. The The imaging element 25 is a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, or the like. The incident light is photoelectrically converted by the image sensor 25, and the analog signal that is the output is converted to a digital signal by the A / D converter 26. The digital signal is subjected to processing such as gamma correction, color separation, and color difference matrix by the camera DSP 27, and a standard television signal is generated by adding a synchronization signal. Furthermore, brightness data for exposure control is transmitted to the CPU 28 by the camera DSP 27, and an image processed by the camera DSP 27 is stored in the memory 29 or displayed on the display 16.

  The CPU 28 performs an exposure control calculation based on the luminance data transmitted from the camera DSP 27. When the calculation result is not appropriate for exposure, the diaphragm driving device 50 and the ND filter driving device 70 are controlled so as to be appropriate. For example, when exposure control is performed in the direction in which the amount of incident light is reduced from the state in which the aperture opening / closing device 40 and the ND filter opening / closing device 60 are open, the aperture opening / closing device 40 is driven by controlling the aperture driving device 50 to Decrease the amount of opening. Next, the ND filter driving device 70 is controlled to drive the ND filter opening / closing device 60 to reduce the amount of incident light passing through the aperture opening.

  More specifically, in this case, when the aperture opening / closing device 40 is driven by the aperture driving device 50, if the aperture amount of the aperture opening is reduced to the pinhole state, a diffraction phenomenon occurs, resulting in a so-called small aperture state. End up. Therefore, when the small aperture state is reached, the ND filter driving device 70 is controlled by the command from the CPU 28 and the ND filter opening / closing device 60 is driven. Then, by closing the front side of the aperture opening with an ND filter, the amount of incident light passing through the aperture opening is reduced, and the amount of light incident on the image sensor 25 is reduced. Thereafter, the CPU 28 controls the aperture driving device 50 based on the reduced incident light quantity, and drives the aperture opening / closing device 40 to increase the aperture amount of the aperture opening. As a result, the small aperture state is canceled and so-called small aperture blur can be avoided.

  On the other hand, when the photographing is changed from photographing a bright subject whose aperture is closed with an ND filter to photographing a subject such as a shade, the amount of light incident on the image sensor 25 decreases. Therefore, the ND filter driving device 70 is controlled by a command from the CPU 28, and the ND filter opening / closing device 60 is driven to retract the ND filter from the front side of the aperture opening. At the same time, the CPU 28 controls the aperture driving device 50 to drive the aperture opening / closing device 40 so that the aperture amount of the aperture opening corresponds to the amount of incident light.

<1. First Embodiment>
[Configuration example of light intensity adjustment device]

FIG. 4 is an exploded perspective view showing the configuration of the light amount adjusting device 30 as one embodiment (first embodiment) of the light amount adjusting device of the present invention.
As shown in FIG. 4, the light amount adjusting device 30 includes a ground plate 31, a partition plate 34, and a pressing plate 36.

  The light quantity adjusting device 30 includes an upper diaphragm blade 41 (corresponding to the first diaphragm blade in the present invention) and a lower diaphragm blade 44 (second diaphragm in the present invention) constituting the diaphragm opening / closing device 40 (see FIG. 3). Equivalent to a blade). Furthermore, it has an aperture drive motor 51 (corresponding to aperture blade drive means in the present invention) and an aperture drive arm 52 constituting an aperture drive device 50 (see FIG. 3). The diaphragm drive motor 51 is a stepping motor in this embodiment, but a linear motor or the like can also be used.

  Further, the light amount adjusting device 30 includes an upper ND blade 61 (corresponding to the light-reducing filter blade in the present invention) and a lower ND blade 64 (light-reducing in the present invention) constituting the ND filter opening / closing device 60 (see FIG. 3) Equivalent to filter blades). The upper ND blade 61 holds an upper ND filter 67 (corresponding to the first neutral density filter in the present invention) having a constant transmittance, and the lower ND blade 64 has a constant transmittance. The lower ND filter 68 (corresponding to the second neutral density filter in the present invention) is held. Further, it has an ND drive motor 71 (corresponding to the neutral density filter drive means in the present invention) and an ND drive arm 72 constituting the ND filter drive device 70 (see FIG. 3). The ND drive motor 71 is a stepping motor in this embodiment, but a linear motor or the like can also be used.

  Here, the base plate 31 is formed with a circular opening 31a for allowing light to enter, and is arranged in a direction perpendicular to the optical axis of the incident light from the opening 31a. . Further, the ground plate 31 is provided with a guide rail 32 integrally formed and a convex rail 33. The upper ND blade 61 has a guide hole 62 into which the guide pin 32 is inserted, and the lower ND blade 64 has a guide hole 65 into which the guide pin 32 is inserted. Therefore, the upper ND blade 61 and the lower ND blade 64 are independently attached along the surface of the main plate 31 by inserting the guide pin 32 into the guide hole 62 and the guide hole 65. Moreover, since the guide hole 62 and the guide hole 65 are formed as long holes, the upper ND blade 61 and the lower ND blade 64 are perpendicular to the optical axis of the incident light while the frictional force is reduced on the rail 33. Can reciprocate in the direction.

  The partition plate 34 is for avoiding contact between the upper ND blade 61 and the lower ND blade 64, and the upper diaphragm blade 41 and the lower diaphragm blade 44, and is formed of, for example, a stainless steel plate or the like on both the front and back surfaces. A rail 35 is provided. The upper diaphragm blade 41 has a guide hole 42 into which the guide pin 32 is inserted, and the lower diaphragm blade 44 has a guide hole 45 into which the guide pin 32 is inserted. Therefore, the upper diaphragm blade 41 and the lower diaphragm blade 44 are independently attached along the surface of the base plate 31 via the partition plate 34 by inserting the guide pins 32 into the guide holes 42 and 45. Become. Moreover, since the guide hole 42 and the guide hole 45 are formed as long holes, the upper diaphragm blade 41 and the lower diaphragm blade 44 are perpendicular to the optical axis of the incident light while reducing the frictional force on the rail 35. Can reciprocate in the direction.

  Furthermore, the surfaces of the upper diaphragm blade 41 and the lower diaphragm blade 44 are blocked by a pressing plate 36 (for example, a stainless plate or the like having rails). An ND drive motor 71 is disposed on the base plate 31 side, and an ND drive arm 72 is attached to the ND drive motor 71. An upper ND drive pin 73 and a lower ND drive pin 74 are integrally formed at both ends of the ND drive arm 72. The cam hole 63 and the cam hole 66 formed in the upper ND blade 61 and the lower ND blade 64 are individually formed. Get stuck. On the other hand, an aperture drive motor 51 is disposed on the holding plate 36 side, and an aperture drive arm 52 is attached to the aperture drive motor 51. An upper diaphragm driving pin 53 and a lower diaphragm driving pin 54 are integrally formed at both ends of the diaphragm driving arm 52, and are individually formed with the cam hole 43 and the cam hole 46 formed in the upper diaphragm blade 41 and the lower diaphragm blade 44, respectively. Get stuck. The presser plate 36 and the partition plate 34 are fixed to the base plate 31 by means such as snap fit. The diaphragm drive motor 51 is fixed to the holding plate 36 by screw fastening or adhesion, and the ND drive motor 71 is fixed to the base plate 31 by screw fastening or adhesion.

  The cam hole 43 and the cam hole 46 of the upper diaphragm blade 41 and the lower diaphragm blade 44 convert the forward / reverse rotation of the diaphragm driving arm 52 into the reciprocating movement of the upper diaphragm blade 41 and the lower diaphragm blade 44. Therefore, if the diaphragm drive arm 52 is rotated forward and backward by the diaphragm drive motor 51, the driving force of the diaphragm drive motor 51 is transmitted through the cam hole 43 and the cam hole 46. As a result, the upper diaphragm blade 41 and the lower diaphragm blade 44 are guided by the guide pin 32 and reciprocate between a fully opened position where the opening 31a is fully opened and a diaphragm position where the opening amount of the opening 31a is reduced. Further, since the upper diaphragm blade 41 and the lower diaphragm blade 44 move linearly in opposite directions, the upper diaphragm blade 41 and the lower diaphragm blade 44 are formed on the surface side of the opening 31a by the diaphragm drive motor 51. The aperture amount of the diaphragm aperture can be increased or decreased.

  Similarly, the cam hole 63 and the cam hole 66 of the upper ND blade 61 and the lower ND blade 64 convert the forward / reverse rotation of the ND drive arm 72 into a reciprocating movement of the upper ND blade 61 and the lower ND blade 64. Therefore, when the ND drive arm 72 is rotated forward and backward by the ND drive motor 71, the driving force of the ND drive motor 71 is transmitted through the cam hole 63 and the cam hole 66. As a result, the upper ND blade 61 and the lower ND blade 64 are guided by the guide pin 32, and the upper ND filter 67 and the lower ND filter 68 are located between the retracted position away from the aperture opening and the shielding position covering all the aperture openings. Move back and forth.

  Here, for example, the outer shape of the upper diaphragm blade 41 is formed so as to avoid the movement of the lower diaphragm driving pin 54 on the opposite side of the upper diaphragm driving pin 53 fitted in the cam hole 43 of the upper diaphragm blade 41. Yes. The outer shapes of the lower diaphragm blade 44, the upper ND blade 61, and the lower ND blade 64 are also formed in the same manner. Therefore, the upper aperture blade 41, the lower aperture blade 44, the upper ND blade 61, and the lower ND blade 64 can reciprocate without interfering with each other. In addition, the upper diaphragm blade 41, the lower diaphragm blade 44, the upper ND blade 61, and the lower ND blade 64 can be assembled by being dropped onto the surface of the base plate 31, and the thickness can be reduced. And miniaturized.

  Further, the retracted position of the upper ND filter 67 and the lower ND filter 68 and the fully opened position of the upper diaphragm blade 41 and the lower diaphragm blade 44 overlap vertically on the surface of the main plate 31. Specifically, the upper ND filter 67 is disposed so as to overlap the upper diaphragm blade 41, and the lower ND filter 68 is disposed so as to overlap the lower diaphragm blade 44. Therefore, the arrangement space of the upper diaphragm blade 41 and the lower diaphragm blade 44, the upper ND filter 67, and the lower ND filter 68 can be shared, and the light amount adjusting device 30 is downsized.

  Furthermore, the ND drive motor 71 moves the upper ND filter 67 straight in the same direction as the upper diaphragm blade 41 and moves the lower ND filter 68 straight in the same direction as the lower diaphragm blade 44. Then, the state where the upper ND filter 67 and the lower ND filter 68 are in the retracted position, the state where only the lower ND filter 68 is in the shielding position, and the state where the upper ND filter 67 and the lower ND filter 68 are in the shielding position are switched. Therefore, the amount of light passing through the aperture opening can be increased or decreased by the ND drive motor 71. In this embodiment, the transmittance of the upper ND filter 67 and the lower ND filter 68 is the same and constant, but the transmittance is different between the two, or the transmittance of one or both is partially changed. Also good.

[Example of operation of light intensity adjustment device]

FIG. 5 is a front view showing a first stage (FIG. 5A) and a second stage (FIG. 5B) of the diaphragm operation in the light amount adjusting device 30 of the first embodiment.
FIG. 6 is a front view showing a third stage (FIG. 6C) and a fourth stage (FIG. 6D) of the diaphragm operation in the light amount adjusting device 30 of the first embodiment.
FIG. 7 is a front view showing a fifth stage (FIG. 7E) of the diaphragm operation in the light amount adjusting device 30 of the first embodiment.

  In the first stage of the diaphragm operation shown in FIG. 5A, the upper diaphragm blade 41 and the lower diaphragm blade 44 are in the fully open position. Therefore, the aperture opening 37 formed on the surface side of the opening 31a (see FIG. 4) by the upper diaphragm blade 41 and the lower diaphragm blade 44 has the maximum opening amount, and the opening 31a is fully opened. Further, since both the upper ND filter 67 and the lower ND filter 68 are in the retracted position, the amount of light passing through the aperture opening 37 is not reduced.

  Next, in the second stage of the diaphragm operation shown in FIG. 5B, the upper diaphragm blade 41 and the lower diaphragm blade 44 are moved to the diaphragm position by the diaphragm drive motor 51 (see FIG. 4), so that the aperture amount of the diaphragm opening 37 is increased. Decrease. This diaphragm position is set in a range where the small diaphragm state does not occur (diffraction degradation does not occur).

  Subsequently, in the third stage of the diaphragm operation shown in FIG. 6C, only the lower ND filter 68 is set to the shielding position while the upper diaphragm blade 41 and the lower diaphragm blade 44 are maintained at the diaphragm position. Specifically, the ND drive motor 71 is rotated slightly clockwise, and the upper ND blade 61 is lowered and the lower ND blade 64 is raised by the ND drive arm 72. Therefore, the upper ND filter 67 is lowered and the lower ND filter 68 is raised. However, in the light amount adjusting device 30 according to the first embodiment, the upper and lower widths of the upper ND filter 67 are small and the upper and lower widths of the lower ND filter 68 are small. It is getting bigger. Therefore, the lower end of the upper ND filter 67 is still a retracted position away from the aperture opening 37, and only the lower ND filter 68 is a shielding position covering the entire aperture opening 37. As a result, it is possible to suppress the occurrence of diffraction degradation due to a small aperture. Further, it is possible to avoid a diffraction phenomenon due to half-hanging of the upper ND filter 67 or the lower ND filter 68 and image quality deterioration due to reflection of the end face. Note that the upper ND filter 67 or the lower ND filter 68 can be in a half-hanging state depending on the rotation state of the ND drive motor 71.

  Here, at the time of moving image shooting, it is desirable to perform the third stage aperture operation shown in FIG. Further, when the lower ND filter 68 is set to the shielding position, the upper diaphragm blade 41 and the lower diaphragm blade 44 may be slightly moved. At this time, by changing the gain of the amplifier and the shutter speed of the electronic shutter, the exposure change due to the insertion and removal of the lower ND filter 68 (and the movement of the upper diaphragm blade 41 and the lower diaphragm blade 44) is offset. And continuous exposure control.

  In the fourth stage of the diaphragm operation shown in FIG. 6D, the upper ND filter 67 is also set to the shielding position while the upper diaphragm blade 41 and the lower diaphragm blade 44 are maintained at the diaphragm position. Specifically, the ND drive motor 71 is rotated largely clockwise, and the ND drive arm 72 further lowers the upper ND blade 61 and raises the lower ND blade 64. Therefore, not only the lower ND filter 68 but also the upper ND filter 67 is a shielding position that covers the entire aperture opening 37. Therefore, the amount of light passing through the aperture opening 37 can be further reduced. Since the lower ND filter 68 has a large vertical width, even if it further rises from the shielding position shown in FIG. Further, when the upper ND filter 67 is set to the shielding position, the upper diaphragm blade 41 and the lower diaphragm blade 44 may be moved somewhat. In this case, continuous exposure control is performed by canceling the exposure change.

  Finally, in the fifth stage of the diaphragm operation shown in FIG. 7E, the upper diaphragm blade 41 and the lower diaphragm blade 44 are further narrowed down. Thereby, even after both the upper ND filter 67 and the lower ND filter 68 have moved to the shielding position, the amount of light incident on the image sensor 25 (see FIG. 3) can be reduced. In the first embodiment, the upper diaphragm blade 41 and the lower diaphragm blade 44 are narrowed down to the fully closed state, so that the shutter function of the upper diaphragm blade 41 and the lower diaphragm blade 44 can be shared.

  As described above, the upper diaphragm blade 41, the lower diaphragm blade 44, the upper ND blade 61, and the lower ND blade 64 are connected to the cam hole 43, the cam hole 46, the cam hole 63, and the cam hole 66 shown in FIG. The diaphragm operation shown in FIGS. 5, 6, and 7 is performed according to the relationship among the drive pin 53, the lower diaphragm drive pin 54, the upper ND drive pin 73, and the lower ND drive pin 74. Then, by setting the formation position and angle of the cam hole 43, the cam hole 46, the cam hole 63, and the cam hole 66, from the first stage shown in FIG. 5A to the fifth stage shown in FIG. 7E. The rotation angle of the aperture drive arm 52 (see FIG. 4) and the ND drive arm 72 (see FIG. 4) is 75 °. In order to reduce the pressure angle of the cam hole 43, the cam hole 46, the cam hole 63, and the cam hole 66 at each stage, the rotation angle of the aperture drive arm 52 and the ND drive arm 72 assigned to each stage may be increased. . In recent years, the reading speed of the image pickup element 25 (see FIG. 3) has been increased (particularly, a CMOS image sensor), and therefore it is no longer necessary to use a mechanical shutter function. Therefore, the rotation angle of the aperture driving arm 52 from the fourth stage shown in FIG. 6D to the fifth stage shown in FIG. 7E may be reduced, or the fifth stage itself may be omitted.

  The light amount adjusting device 30 according to the first embodiment can avoid a diffraction phenomenon caused by a small stop, a diffraction phenomenon caused by half-hanging of the upper ND filter 67 or the lower ND filter 68, and end face reflection. Further, exposure control is possible with the upper ND filter 67 and the lower ND filter 68, while maintaining a diaphragm shape with less diffraction degradation than the conventional one for a longer time. Furthermore, even with a subject having the same brightness, the upper ND filter 67 and the lower ND filter 68 can be taken in and out in a state where the aperture shape is made smaller with priority on the depth of field. Furthermore, after the lower ND filter 68 is set to the shielding position, the selection of the exposure and the depth of field can be increased, for example, the aperture is further reduced and the upper ND filter 67 is also set to the shielding position. Control becomes possible.

<2. Second Embodiment>
[Example of operation of light intensity adjustment device]

FIG. 8 is a front view showing a first stage (FIG. 8A) and a second stage (FIG. 8B) of the diaphragm operation in the light amount adjusting device 80 of the second embodiment.
FIG. 9 is a front view showing a third stage (FIG. 9C) and a fourth stage (FIG. 9D) of the diaphragm operation in the light amount adjusting device 80 of the second embodiment.
FIG. 10 is a front view showing a fifth stage (FIG. 10E) and a sixth stage (FIG. 10F) of the diaphragm operation in the light amount adjusting device 80 of the second embodiment.
Further, FIG. 11 is a front view showing a seventh stage (FIG. 11G) of the diaphragm operation in the light amount adjusting device 80 of the second embodiment.

  The light amount adjusting device 80 of the second embodiment shown in FIGS. 8, 9, 10, and 11 is the light amount adjusting device 30 of the first embodiment (see FIGS. 5, 6, and 7). On the other hand, upper ND blades 81 and lower ND blades 82 having different shapes (in particular, cam holes) are used. Further, an ND drive arm 83 having a shape corresponding to the upper ND blade 81 and the lower ND blade 82 is used. Therefore, the movement of the upper ND filter 67 and the lower ND filter 68 changes. Specifically, in the first stage of the diaphragm operation shown in FIG. 8A, the upper diaphragm blade 41 and the lower diaphragm blade 44 are in the fully open position. Therefore, the aperture opening 37 formed on the surface side of the opening 31a (see FIG. 4) by the upper diaphragm blade 41 and the lower diaphragm blade 44 has the maximum opening amount, and the opening 31a is fully opened. Further, since both the upper ND filter 67 and the lower ND filter 68 are in the retracted position, the amount of light passing through the aperture opening 37 is not reduced.

  Next, in the second stage of the aperture operation shown in FIG. 8B, the aperture drive motor 51 (see FIG. 4) moves the upper aperture blade 41 and the lower aperture blade 44 to the aperture position, so that the aperture amount of the aperture opening 37 is increased. Decrease. This diaphragm position is set in a range where the small diaphragm state does not occur (diffraction degradation does not occur).

  Subsequently, in the third stage of the diaphragm operation shown in FIG. 9C and the fourth stage of the diaphragm operation shown in FIG. 9D, the upper diaphragm blade 41 and the lower diaphragm blade 44 are maintained at the diaphragm position while the Only the ND filter 68 is set to the shielding position. Specifically, in the third stage shown in FIG. 9C, the ND drive motor 71 is rotated slightly clockwise, and the lower ND blade 82 is raised by the ND drive arm 83. At this time, in the light amount adjusting device 80 of the second embodiment, the upper ND blade 81 (upper ND filter 67) does not descend and does not move from the retracted position. This is because the cam hole is formed concentrically so as to move along the cam hole of the upper ND blade 81 even if the ND drive arm 83 rotates clockwise.

  Thereafter, when the ND drive motor 71 (ND drive arm 83) is rotated clockwise until the fourth stage shown in FIG. 9D, the lower ND blade 82 is further raised and the upper ND blade 67 is slightly lowered. Therefore, the lower end of the upper ND filter 67 is still a retracted position away from the aperture opening 37, and only the lower ND filter 68 is a shielding position covering the entire aperture opening 37. Therefore, the ND drive motor 71 holds the upper ND filter 67 in the retracted position until the lower ND filter 68 is moved to the shielding position. Then, the occurrence of diffraction degradation due to a small aperture is suppressed. In addition, a diffraction phenomenon due to half-hanging of the upper ND filter 67 or the lower ND filter 68 and image quality deterioration due to reflection of the end face can be avoided.

  In the fifth stage of the diaphragm operation shown in FIG. 10 (e) and the sixth stage of the diaphragm operation shown in FIG. 10 (f), the upper ND filter 67 while the upper diaphragm blade 41 and the lower diaphragm blade 44 are maintained at the diaphragm position. Is also in the shielding position. Specifically, in the fifth stage shown in FIG. 10 (e), the ND drive motor 71 is further rotated clockwise, and the ND drive arm 83 further lowers the upper ND blade 81 and raises the lower ND blade 82. Let

  Thereafter, when the ND drive motor 71 (ND drive arm 83) is rotated clockwise until the sixth stage shown in FIG. 10 (f), the upper ND blade 81 is further lowered. Therefore, not only the lower ND filter 68 but also the upper ND filter 67 is a shielding position that covers the entire aperture opening 37. Therefore, the amount of light passing through the aperture opening 37 can be further reduced. At this time, in the light amount adjustment device 80 according to the second embodiment, the lower ND blade 82 (lower ND filter 68) does not move from the fifth-stage shielding position shown in FIG. This is because the cam hole is formed concentrically so as to move along the cam hole of the lower ND blade 82 even if the ND drive arm 83 rotates clockwise.

  Finally, in the seventh stage of the diaphragm operation shown in FIG. 11G, the upper diaphragm blade 41 and the lower diaphragm blade 44 are further narrowed down. Thereby, even after both the upper ND filter 67 and the lower ND filter 68 have moved to the shielding position, the amount of light incident on the image sensor 25 (see FIG. 3) can be reduced. In the second embodiment, the upper diaphragm blades 41 and the lower diaphragm blades 44 are narrowed to the fully closed state, so that the shutter functions of the upper diaphragm blades 41 and the lower diaphragm blades 44 can be shared.

<3. Third Embodiment>
[Configuration example of light intensity adjustment device]

FIG. 12 shows a light amount adjusting device 30 (FIG. 12A) and a light amount adjusting device 90 (FIG. 12) as embodiments of the light amount adjusting device of the present invention (first embodiment, third embodiment). It is a front view which shows the structure of (b)).
As shown in FIG. 12A, in the light amount adjusting device 30 of the first embodiment, the upper and lower widths of the upper ND filter 67 are small and the vertical width of the lower ND filter 68 is large. On the other hand, as shown in FIG. 12B, in the light amount adjustment device 90 of the third embodiment, the upper and lower widths of the upper ND filter 93 are large and the vertical width of the lower ND filter 94 is small. Further, in the light amount adjusting device 90 of the third embodiment, the upper ND blade 91 and the lower ND blade 92 having shapes matching the upper ND filter 93 and the lower ND filter 94 are used. Furthermore, an ND drive arm 95 having a shape corresponding to the upper ND blade 91 and the lower ND blade 92 is used.

  Here, in the light amount adjustment device 30 (FIG. 12A) of the first embodiment, the distance from the optical axis to the upper end of the light amount adjustment device 30 is L1, and the distance from the optical axis to the lower end of the light amount adjustment device 30. When L2 is L2, L1> L2. Therefore, the length on the ND drive motor 71 side from the optical axis can be shortened. On the other hand, in the light amount adjustment device 90 (FIG. 12B) of the third embodiment, the distance from the optical axis to the upper end of the light amount adjustment device 90 is L′ 1, and from the optical axis to the lower end of the light amount adjustment device 90. When the distance is L′ 2, L′ 1 <L′ 2. Therefore, the length opposite to the ND drive motor 71 from the optical axis can be shortened. Therefore, the light amount adjusting device 30 (FIG. 12A) or the light amount adjusting device 90 (FIG. 12B) may be arbitrarily selected according to the outer shape of the lens barrel 20 (see FIG. 2).

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible. For example, in the embodiment, the digital still camera 10 is taken as an example of the imaging device. However, the present invention is not limited to this, and can be widely applied to imaging apparatuses such as digital video cameras. Further, in the embodiment, the upper ND filter 67 and the lower ND filter 68 are held by the upper ND blade 61 and the lower ND blade 64, but the upper ND filter and the lower ND filter themselves may have a blade shape. Furthermore, in the embodiment, two sheets of the upper ND filter 67 and the lower ND filter 68 are reciprocated by one ND drive motor 71. However, by increasing the number of ND drive motors and ND filter drive pins, each of them may reciprocate using three or more ND filters. Further, the neutral density filter is not limited to the ND filter, and may be a liquid crystal filter or the like that can change the transmittance.

It is a perspective view showing a digital still camera as one embodiment of an imaging device of the present invention. It is sectional drawing of the optical axis direction of the lens barrel as one Embodiment of the lens barrel of this invention. 1 is a block diagram illustrating a configuration of a digital still camera as an embodiment of an imaging apparatus of the present invention. It is a disassembled perspective view which shows the structure of the light quantity adjustment apparatus as one Embodiment (1st Embodiment) of the light quantity adjustment apparatus of this invention. It is a front view which shows the 1st step and 2nd step of the aperture operation in the light quantity adjustment apparatus of 1st Embodiment. It is a front view which shows the 3rd step and the 4th step of the aperture operation in the light quantity adjustment apparatus of 1st Embodiment. It is a front view which shows the 5th step of the aperture_diaphragm | restriction operation | movement in the light quantity adjustment apparatus of 1st Embodiment. It is a front view which shows the 1st step and 2nd step of an aperture operation in the light quantity adjustment apparatus of 2nd Embodiment. It is a front view which shows the 3rd step and 4th step of the aperture operation in the light quantity adjustment apparatus of 2nd Embodiment. It is a front view which shows the 5th step and the 6th step of the aperture operation in the light quantity adjustment apparatus of 2nd Embodiment. It is a front view which shows the 7th step | stage of the aperture operation in the light quantity adjustment apparatus of 2nd Embodiment. It is a front view which shows the structure of the light quantity adjustment apparatus as embodiment (1st Embodiment, 3rd Embodiment) of the light quantity adjustment apparatus of this invention.

Explanation of symbols

10 Digital still camera (imaging device)
DESCRIPTION OF SYMBOLS 20 Lens barrel 20a Lens barrel body 21 Lens 25 Image pick-up element 30 Light quantity adjustment device 31 Base plate 31a Opening 34 Partition plate 37 Aperture opening 40 Aperture opening / closing device (part of light quantity adjustment device)
41 Upper diaphragm blade (first diaphragm blade)
44 Lower diaphragm blade (second diaphragm blade)
50 Aperture driving device (aperture blade driving means)
51 Aperture drive motor (aperture blade drive means)
60 ND filter opening / closing device (part of the light amount adjusting device)
61 Upper ND blade (Damping filter blade)
63 Cam hole 64 Lower ND blade (Damping filter blade)
66 Cam hole 67 Upper ND filter (first neutral density filter)
68 Lower ND filter (second neutral density filter)
70 ND filter driving device (dimming filter driving means)
71 ND drive motor (dimming filter driving means)
72 ND drive arm (dimming filter drive arm)
73 Upper ND drive pin (dimming filter drive pin)
74 Lower ND drive pin (dimming filter drive pin)
81 Upper ND blade (Damping filter blade)
82 Lower ND blade (Light attenuation filter blade)
83 ND drive arm (dimming filter drive arm)
91 Upper ND blade (Light attenuation filter blade)
92 Lower ND blade (Damping filter blade)
93 Upper ND filter (first neutral density filter)
94 Lower ND filter (second neutral density filter)
95 ND drive arm (dimming filter drive arm)

Claims (8)

An opening for allowing light to enter, and a ground plane disposed in a direction perpendicular to the optical axis of incident light from the opening;
A plurality of independent aperture blades attached along the surface of the base plate and capable of reciprocating between a fully open position for fully opening the opening and an aperture position for reducing the opening amount of the opening;
A diaphragm blade driving means that moves each diaphragm blade and increases or decreases the opening amount of the diaphragm opening formed on the surface side of the opening by each diaphragm blade;
A plurality of units that are attached along the surface of the main plate and that can reciprocate between a retracted position away from the diaphragm opening and a shielding position that covers all the diaphragm openings to increase or decrease the amount of light passing through the diaphragm opening. Independent neutral density filter,
Each of the neutral density filters is moved, all the neutral density filters are in the retracted position, only some of the neutral density filters are in the shield position, and all the neutral density filters are in the shield position A light amount adjusting device comprising: a neutral density filter driving means for switching between. The light amount adjusting device according to claim 1,
The light amount adjusting device in which the retracting position of each of the neutral density filters and the fully open position of each of the diaphragm blades overlap vertically on the surface of the base plate. The light amount adjusting device according to claim 1,
The neutral density filter driving means holds the other neutral density filter in the retracted position until one neutral density filter is moved to the shielding position. The light amount adjusting device according to claim 1,
The diaphragm blade is composed of a first diaphragm blade and a second diaphragm blade,
The diaphragm blade driving means linearly moves the first diaphragm blade and the second diaphragm blade in opposite directions,
The neutral density filter includes a first neutral density filter disposed so as to overlap the first diaphragm blades and a second neutral density filter disposed so as to overlap the second diaphragm blades,
The neutral density filter driving means linearly moves the first neutral density filter in the same direction as the first diaphragm blade, and linearly moves the second neutral density filter in the same direction as the second diaphragm blade. . The light amount adjusting device according to claim 1,
A neutral density filter driving arm that rotates forward and backward by the neutral density filter driving means;
A plurality of independent neutral density filter blades individually holding each neutral density filter;
In the neutral density filter drive arm, the same number of neutral density filter drive pins as the neutral density filter blades are formed.
Each of the neutral density filter blades is individually fitted with each of the neutral density filter drive pins, and a cam hole for converting forward / reverse rotation of the neutral density filter drive arm into a reciprocating movement of each of the neutral density filter blades. The light quantity adjustment device is formed. The light amount adjusting device according to claim 1,
A light quantity adjusting device having a partition plate between each of the diaphragm blades and each of the neutral density filters to avoid contact between the two. An imaging lens;
A lens barrel body for housing the lens;
An opening for allowing light from the lens to enter, and a ground plane disposed in a direction perpendicular to the optical axis of the incident light from the opening;
A plurality of independent aperture blades attached along the surface of the base plate and capable of reciprocating between a fully open position for fully opening the opening and an aperture position for reducing the opening amount of the opening;
A diaphragm blade driving means that moves each diaphragm blade and increases or decreases the opening amount of the diaphragm opening formed on the surface side of the opening by each diaphragm blade;
A plurality of units that are attached along the surface of the main plate and that can reciprocate between a retracted position away from the diaphragm opening and a shielding position that covers all the diaphragm openings to increase or decrease the amount of light passing through the diaphragm opening. Independent neutral density filter,
Each of the neutral density filters is moved, all the neutral density filters are in the retracted position, only some of the neutral density filters are in the shield position, and all the neutral density filters are in the shield position A lens barrel having a neutral density filter driving means for switching between. An imaging lens;
A lens barrel body for housing the lens;
An opening for allowing light from the lens to enter, and a ground plane disposed in a direction perpendicular to the optical axis of the incident light from the opening;
An image sensor disposed on the optical axis behind the base plate in the incident direction;
A plurality of independent aperture blades attached along the surface of the base plate and capable of reciprocating between a fully open position for fully opening the opening and an aperture position for reducing the opening amount of the opening;
A diaphragm blade driving means that moves each diaphragm blade and increases or decreases the opening amount of the diaphragm opening formed on the surface side of the opening by each diaphragm blade;
A plurality of units that are attached along the surface of the main plate and that can reciprocate between a retracted position away from the diaphragm opening and a shielding position that covers all the diaphragm openings to increase or decrease the amount of light passing through the diaphragm opening. Independent neutral density filter,
Each of the neutral density filters is moved, all the neutral density filters are in the retracted position, only some of the neutral density filters are in the shield position, and all the neutral density filters are in the shield position And an attenuating filter driving means for switching between.

Images