JP2011138080A - Lens barrel and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a lens barrel in the optical axis and radial directions thereof. <P>SOLUTION: The lens barrel has an aperture 50a configured such that at least part of an optical lens is telescoped in the optical axis direction, and a diaphragm blade 53 that is arranged movably between a closing position entering the aperture 50a and an opening position retreating from the aperture 50a. The diaphragm blade 53 is configured to leave part of the aperture 50a outside an effective luminous flux range 22b (have a gap 50b) in the closing position, and to telescope at least part of the optical lens in the optical axis direction inside the aperture 50a in the opening position, wherein a passage cross section of the aperture 50a by a luminous flux, which passes the aperture 50a and forms an image in an effective imaging range on an imaging plane, is the effective luminous flux range 22b. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lens barrel provided with a light amount adjusting device for adjusting a light amount incident from an imaging lens, and an imaging device.

  2. Description of the Related Art Conventionally, an imaging apparatus such as a digital video camera or a digital still camera forms a subject image with an imaging lens, and a CCD (Charge Coupled Device Image Sensor) image sensor or a CMOS (Complementary Metal Oxide) disposed at the rear of the imaging lens. Semiconductor) A subject image is captured by an image sensor such as an image sensor. In order to adjust the amount of light reaching the effective imaging range of the image sensor with respect to incident light from the imaging lens, a lens barrel provided with a light amount adjusting device is known.

  Here, in the lens barrel that the imaging lens is extended at the time of shooting and retracted at the time of non-shooting, a part of the imaging lens in the optical axis direction when retracted enters the opening of the light amount adjusting device, so that the lens mirror A technique is known that enables downsizing of the cylinder in the optical axis direction. Specifically, it is a technology that shortens the length in the optical axis direction by allowing the imaging lens to enter and exit the aperture when the aperture blade or shutter blade that opens and closes the aperture of the light amount adjustment device is open. is there.

FIG. 18 is a cross-sectional view showing the periphery of the light amount adjusting devices 150 and 250 in the lens barrels 120 and 220 of the conventional example.
The lens barrel 120 shown in the upper diagram of FIG. 18 has a lens group 122 held by a lens moving frame 134, and the lens group 122 can move in the direction of the optical axis 120a by the movement of the lens moving frame 134. . In addition, a light amount adjusting device 150 is disposed behind the direction of the optical axis 120a (below the lens moving frame 134 in FIG. 18). The light amount adjusting device 150 has a shutter blade and a diaphragm blade, and adjusts the light amount by opening and closing the opening 150a. The aperture 150a is set to be larger than the effective luminous flux range 122b when the cross section of the aperture 150a passing through the aperture 150a and forming an image in the effective imaging range is defined as the effective luminous flux range 122b. .

  On the other hand, the lens barrel 220 shown in the lower diagram of FIG. 18 allows the lens barrel 120 to be downsized in the direction of the optical axis 120a. Specifically, the opening 250a of the light amount adjusting device 250 is made larger than the lens outer diameter 122a so that a part of the lens group 122 moved by the lens moving frame 234 can enter and leave the opening 250a. Therefore, the length L2 in the direction of the optical axis 120a when the lens barrel 220 is retracted can be shorter than the length L1 in the direction of the optical axis 20a when the lens barrel 120 is retracted.

JP 2003-66311 A

  However, in the technique of the above-mentioned Patent Document 1 (the lens barrel 220 shown in the lower diagram of FIG. 18), the opening 250a of the light amount adjusting device 250 needs to be set large, so that the radial direction of the lens barrel 220 increases. End up. More specifically, in the case of the lens barrel 120 shown in the upper diagram of FIG. 18, the opening 150 a of the light amount adjusting device 150 only needs to be slightly larger than the effective light beam range 122 b of the lens group 122. However, in order to allow the lens group 122 to enter and exit from the opening 250a of the light amount adjusting device 250 as in the lens barrel 220 shown in the lower diagram of FIG. 18, the lens group is not only larger than the effective light beam range 122b but also a lens. It must be larger than the outer diameter 122a. Therefore, it is necessary to increase the size of the diaphragm blade that closes the opening 250a, so that the outer diameter D2 of the lens barrel 220 is larger than the outer diameter D1 of the lens barrel 120.

  As described above, the configuration in which a part of the lens group 122 is accommodated in the opening 250a of the light amount adjusting device 250 has an advantage that the length L2 of the lens barrel 220 in the direction of the optical axis 120a can be shortened, while the outer diameter D2. Has the disadvantage of becoming larger. Further, it is conceivable to increase the number of diaphragm blades instead of increasing the size of the diaphragm blades in order to open and close the large opening 250a. However, this causes problems of complicated blade structure and high cost.

  Therefore, the problem to be solved by the present invention is to realize downsizing of the lens barrel in the optical axis direction and the radial direction while avoiding cost increase.

The present invention solves the above-described problems by the following means.
According to the first aspect of the present invention, an optical lens that forms at least a part of an imaging optical system, a holding frame that holds the optical lens, and an amount of light that reaches an effective imaging range on an imaging plane are adjusted. A light amount adjusting device, the light amount adjusting device is supported so as to be relatively movable in the optical axis direction with respect to the optical lens, and allows a light beam incident on the optical lens to pass therethrough, and at least a part of the optical lens is An opening formed so as to be able to enter and exit in the optical axis direction, and a light amount adjusting blade provided to be movable between a closed position that enters the opening and an open position that retreats from the opening, and the light amount adjusting blade Is the effective light flux range when the cross section of the aperture of the light beam that passes through the aperture and forms an image in the effective imaging range on the imaging plane is the effective light beam range. Leave some Configured urchin, in the open position, at least a portion of the optical lens inside the opening is a lens barrel that is configured to be out of the optical axis direction.

  The invention described in claim 5 is an image pickup apparatus including the same optical lens, holding frame, and light amount adjustment device as the invention described in claim 1.

(Function)
According to the first and fifth aspects of the present invention, at the opening position of the light quantity adjusting blade, at least a part of the optical lens can enter and exit in the optical axis direction inside the opening. Therefore, the optical lens can be moved into the opening. Further, the light amount adjustment blade is configured to leave a part of the opening outside the effective light flux range at the closed position. Thereby, the magnitude | size of the light quantity adjustment blade | wing with respect to opening can be made small.

  According to the present invention, since the optical lens can be moved into the opening, it is possible to reduce the size of the lens barrel in the optical axis direction. In addition, since the size of the light amount adjustment blade with respect to the opening can be reduced, the lens barrel can be reduced in the radial direction.

It is a front view which shows the structure of the digital still camera as one Embodiment of the imaging device of this invention. 1 is an exploded perspective view showing a main part of a lens barrel for a digital still camera as an embodiment of a lens barrel of the present invention. It is the perspective view and sectional drawing which show the lens barrel of the digital still camera shown in FIG. 1, and shows the pay-out state at the time of tele photography. FIGS. 2A and 2B are a perspective view and a sectional view showing a lens barrel of the digital still camera shown in FIG. It is the perspective view and sectional drawing which show the lens barrel of the digital still camera shown in FIG. 1, and shows the retracted state at the time of non-photographing. It is sectional drawing which shows the peripheral part of the light quantity adjustment apparatus in the lens barrel of the digital still camera shown in FIG. It is the front view and back view of a light quantity adjustment apparatus which are shown in FIG. It is a disassembled perspective view of the light quantity adjustment apparatus shown in FIG. 1 is a front view showing a main part of a light amount adjusting device (first embodiment) in a lens barrel for a digital still camera as an embodiment of a lens barrel of the present invention, which includes a diaphragm blade (open) and a shutter. The state of the blade (open) is shown. 1 is a front view showing a main part of a light amount adjusting device (first embodiment) in a lens barrel for a digital still camera as an embodiment of a lens barrel of the present invention, which includes a diaphragm blade (open) and a shutter. The state of the blade (closed) is shown. 1 is a front view showing a main part of a light amount adjusting device (first embodiment) in a lens barrel for a digital still camera as an embodiment of a lens barrel of the present invention, which includes a diaphragm blade (closed) and a shutter. The state of the blade (open) is shown. It is a front view which shows the principal part of the light quantity adjustment apparatus of a reference example, and shows the state of an aperture blade (closed) and a shutter blade (open). It is a front view which shows the principal part of the light quantity adjustment apparatus of a reference example, and shows the state of an aperture blade (open) and a shutter blade (open). 1 is a front view showing a main part of a light amount adjusting device (first embodiment) in a lens barrel for a digital still camera as an embodiment of a lens barrel of the present invention, which includes a diaphragm blade (closed) and a shutter. The state of the blade (closed) is shown. FIG. 4 is a front view showing a main part (second embodiment) of a light amount adjusting device in a lens barrel for a digital still camera as an embodiment of the lens barrel of the present invention, and shows a diaphragm blade (closed) and a shutter. The state of the blade (open) is shown. FIG. 5 is a front view showing a main part (third embodiment) of a light amount adjusting device in a lens barrel for a digital still camera as an embodiment of the lens barrel of the present invention, and shows a diaphragm blade (open) and a shutter. The state of the blade (open) is shown. It is sectional drawing which shows the peripheral part (4th Embodiment) of the light quantity adjustment apparatus in the lens barrel for digital still cameras as one Embodiment of the lens barrel of this invention. It is sectional drawing which shows the peripheral part of the light quantity adjustment apparatus in the lens barrel of a prior art example.

Hereinafter, embodiments for carrying out the present invention will be described 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. The lens barrel in the present invention is assumed to be the lens barrel 20 for the digital still camera 10 in the following embodiments.
The description will be given in the following order:

1. First embodiment (lens barrel: configuration example of light amount adjusting device)
2. Second embodiment (lens barrel: another configuration example of the light amount adjusting device)
3. Third Embodiment (Lens Barrel: Still Another Configuration Example of Light Amount Adjustment Device)
4). Fourth Embodiment (Lens Barrel: Still Another Configuration Example of Light Amount Adjustment Device)

[External appearance of imaging device]

FIG. 1 is a front view showing a configuration of a digital still camera 10 as an embodiment of an imaging apparatus of the present invention.
As shown in FIG. 1, the digital still camera 10 includes a rectangular parallelepiped body 11 constituting an exterior. A lens barrel 20 is incorporated on the right side of the body 11. In the non-photographing state shown in FIG. 1, the front side of the lens barrel 20 is covered with the barrier unit 40.
In the digital still camera 10 shown in FIG. 1, the left and right refer to the left and right viewed from the front side shown in FIG.

  Further, for example, a strobe light emitting unit 12 is built in the upper left of the lens barrel 20, and for example, a switch unit 13 is built in the left of the strobe light emitting unit 12. Furthermore, on the right side of the lens barrel 20, for example, an AF (Auto Focus) auxiliary light unit 14 is incorporated, and on the left side of the lens barrel 20, for example, a battery 15 is incorporated. Furthermore, for example, a condenser microphone 16 is incorporated in the lower right of the lens barrel 20.

[Configuration example of lens barrel]

FIG. 2 is an exploded perspective view showing a main part of a lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention.
As shown in FIG. 2, the lens barrel 20 sequentially moves the makeup ring 31, the barrier unit 40, the first lens frame 32 that holds the first lens group 21, and the first lens frame 32 from the subject side. A moving frame 33, a second moving frame 34 (corresponding to the holding frame in the present invention) that moves while holding the second lens group 22 (corresponding to the optical lens in the present invention), a rectilinear guide ring 35, a rotating ring 36, and a fixed ring. 37, a rear barrel 38, and the like.
In FIG. 2, illustration of the light amount adjusting device and the like is omitted for convenience of explanation.

Here, the decorative ring 31 is fixed to the first moving frame 33 to adjust the appearance of the lens barrel 20, and the barrier unit 40 including the barrier cover 41, the barrier blade 42, the barrier drive spring 43, and the barrier drive member 44. Protect. The decorative ring 31 is fixed by attaching a double-sided tape with release paper to the front surface of the barrier cover 41 fixed to the first moving frame 33, peeling the release paper, and then covering the decorative ring 31 on the first moving frame 33. By doing. And it is firmly fixed to the first moving frame 33 through the barrier cover 41 by the adhesive force of the double-sided tape.
In addition, as a material of the decorative ring 31, various metals, such as an aluminum alloy and stainless steel, are suitable, but engineering plastics can also be used.

  The barrier unit 40 protects the imaging optical system by closing the optical path that is the imaging aperture during non-imaging. Specifically, an imaging opening 41 a for allowing light to enter the first lens group 21 and the like is formed in the barrier cover 41 disposed in the front portion of the first lens group 21. The barrier driving spring 43 attached between the barrier cover 41 and the barrier blade 42 and the barrier driving member 44 constitute an opening / closing mechanism for the barrier blade 42.

  In such a barrier unit 40, the barrier driving member 44 drives the barrier blades 42 to open and close in accordance with switching between the photographing position and the storage position of the first lens frame 32 (first lens group 21). For example, when the first lens frame 32 is set to the photographing position, the barrier driving member 44 rotates in the direction of arrow B to open the barrier blade 42, and the opening 41a of the barrier cover 41 is opened to emit light to the first lens group 21 and the like. Make it incident. On the contrary, when the first lens frame 32 is set to the storage position, the barrier driving member 44 rotates in the direction of arrow A to close the barrier blade 42 and close the opening 41a of the barrier cover 41 to protect the first lens group 21. .

  The first lens group 21 is attached to the first lens frame 32, and the first lens frame 32 is held by the first moving frame 33. The second lens group 22 is disposed behind the first lens group 21 in the optical axis 20a direction and is held by the second moving frame 34. The first moving frame 33 and the second moving frame 34 are each provided with three cam pins, and the three cams provided on the inner peripheral side of the rotating ring 36 that can rotate around the optical axis 20a. Each is engaged with a groove. Further, the first moving frame 33 and the second moving frame 34 are also engaged with the rectilinear groove of the rectilinear guide ring 35 so as not to be simultaneously rotated by the rotation of the rotating ring 36.

  Here, the rotating ring 36 and the rectilinear guide ring 35 can be moved in a straight line by bayonet fitting so that the rectilinear guide ring 35 is not restricted with respect to the rotation of the rotating ring 36. Further, with respect to the movement of the rotary ring 36 in the direction of the optical axis 20a, the linear guide ring 35 also moves together. Specifically, three cam pins are provided on the rotating ring 36 and are respectively fitted with three cam grooves provided on the inner peripheral side of the fixed ring 37. As the rotating ring 36 rotates with respect to the fixed ring 37, the rotating ring 36 moves in the direction of the optical axis 20 a along the locus of the cam groove of the fixed ring 37. Further, the straight guide ring 35 is provided with five convex portions for fitting with the fixed ring 37, and the five convex portions and the five straight grooves provided on the fixed ring 37 are respectively provided. Mating. Therefore, the linear guide ring 35 can only move in the direction of the optical axis 20a with respect to the fixed ring 37, and movement in the rotational direction is restricted.

Therefore, when the rotating ring 36 is rotated, the rotating ring 36 moves in the direction of the optical axis 20 a while rotating with respect to the fixed ring 37. Further, the linear guide ring 35 moves in the direction of the optical axis 20a integrally with the rotary ring 36 without rotating. Furthermore, the first moving frame 33 and the second moving frame 34 move in the direction of the optical axis 20a along the cam groove of the rotating ring 36 without rotating. As a result, the first moving frame 33 (first lens group 21) moves in the direction of the optical axis 20a according to the rotation of the rotating ring 36 and its position, and retracts or extends. Further, the second moving frame 34 (second lens group 22) moves in the direction of the optical axis 20a in accordance with the rotation of the rotating ring 36 and its position to realize zooming (wide shooting or tele shooting).
When the rotary ring 36 is rotated in one direction, the first moving frame 33 is first extended from the retracted position, and then the second moving frame 34 is moved from the retracted position to the tele end via the wide end. Conversely, when the rotary ring 36 is rotated in the opposite direction, the second moving frame 34 first retracts from the tele end via the wide end, and then the first moving frame 33 retracts from the extended position.

  The stationary ring 37 is held by a rear barrel 38, and a cam surface 38a is formed on the rear barrel 38. The cam surface 38 a comes into contact with the cam surface 44 a formed on the barrier drive member 44. When the distance from the rear barrel 38 is reduced by the movement of the first moving frame 33, the barrier drive member 44 is gradually charged by the contact between the cam surface 38a and the cam surface 44a while the barrier drive spring 43 is gradually charged. It rotates in the direction of arrow A, and the barrier blade 42 is closed. On the contrary, when the distance from the rear barrel 38 increases due to the movement of the first moving frame 33, the cam surface 38a and the cam surface 44a are separated from each other, so that the charge of the barrier drive spring 43 is gradually released and the barrier drive member is released. 44 rotates in the direction of arrow B to open the barrier blade 42.

  Thus, the first moving frame 33 (first lens group 21) is extended or retracted according to the rotation and position of the rotating ring 36, and opens and closes the barrier blades 42. Further, the second moving frame 34 (second lens group 22) moves in the tele direction or the wide direction according to the rotation and position of the rotating ring 36, and a zooming operation is performed. Therefore, a gear train is formed on the outer peripheral surface of the rotary ring 36, and the rotary ring 36 is rotated by driving of a drive motor (not shown) fixed between the fixed ring 37 and the rear barrel 38. It is supposed to be.

[External appearance of lens barrel]

3A and 3B are a perspective view and a cross-sectional view showing the lens barrel 20 of the digital still camera 10 shown in FIG.
FIG. 4 is a perspective view and a cross-sectional view showing the lens barrel 20 of the digital still camera 10 shown in FIG.
5 is a perspective view and a cross-sectional view showing the lens barrel 20 of the digital still camera 10 shown in FIG. 1, and shows a retracted state at the time of non-photographing.
Further, FIG. 6 is a cross-sectional view showing the periphery of the light amount adjusting device 50 in the lens barrel 20 of the digital still camera 10 shown in FIG.
As shown in FIGS. 3 to 5, the lens barrel 20 is a retractable type. The imaging optical system of the lens barrel 20 includes a first lens group 21, a second lens group 22, a light amount adjusting device 50, a third lens group 23, and an image sensor 24 arranged in order from the subject side. .
For example, a CCD image sensor or a CMOS image sensor is used as the image sensor 24.

  Here, the first lens group 21 is extended with respect to the image sensor 24 fixed in the direction of the optical axis 20a at the time of photographing shown in FIGS. The second lens group 22 is held by the second moving frame 34 and moves in the direction of the optical axis 20a. The zooming operation of the optical system is performed by moving the first lens group 21 and the second lens group 22 (second moving frame 34) by a predetermined amount in the direction of the optical axis 20a. Furthermore, the focusing operation of the optical system is performed by moving the third lens group 23 by a predetermined amount in the direction of the optical axis 20a. Then, the first lens group 21, the second lens group 22, and the third lens group 23 form incident light in an effective imaging range of the imaging element 24.

  The light amount adjusting device 50 has a shutter function and an iris function. The light amount reaching the effective imaging range of the image sensor 24 from the second lens group 22 by opening and closing the opening 50a (see FIG. 6). adjust. Therefore, when the cross section of the aperture 50a of the light beam that passes through the aperture 50a and forms an image in the effective imaging range is the effective beam range 22b (see FIG. 6), the aperture 50a is larger than the effective beam range 22b. Is set to

  Furthermore, the opening 50a is formed larger than the lens outer diameter 22a of the second lens group 22, as shown in FIG. Specifically, the opening 50 a is set to maintain a predetermined clearance with respect to the lens outer diameter 22 a of the second lens group 22. Thereby, not only the light beam incident on the second lens group 22 can pass through the opening 50a, but also the optical axis 20a direction of the second lens group 22 moved by the second moving frame 34 can enter and exit the opening 50a ( (See the lower diagram in FIG. 6).

  Further, the light amount adjusting device 50 is held so as to be relatively movable in the direction of the optical axis 20 a with respect to the second moving frame 34, and is urged by the spring 25 in a direction away from the second lens group 22. 3, 4, and 6, the light amount adjusting device 50 and the second lens group 22 move relative to each other in the direction of the optical axis 20 a by the bias of the spring 25, The two lens group 22 is retracted from the opening 50 a of the light amount adjusting device 50.

On the other hand, at the time of non-photographing shown in the lower diagrams of FIGS. 5 and 6, the light amount adjusting device 50 overcomes the bias of the spring 25 by the rear barrel 38 and is pressed toward the second lens group 22, thereby opening the light amount adjusting device 50. A part of the second lens group 22 is accommodated in 50a. Therefore, the length in the direction of the optical axis 20a when the lens barrel 20 is retracted can be shortened. Further, the front side of the first lens group 21 is protected by the barrier unit 40.
The movement of the first lens group 21 and the second lens group 22 in the direction of the optical axis 20a is controlled by a cam feeding mechanism (a mechanism constituted by the cam pins 39 shown in FIG. 6) and a drive motor (not shown). Realized.

7 is a front view and a rear view of the light amount adjusting device 50 shown in FIG.
FIG. 8 is an exploded perspective view of the light amount adjusting device 50 shown in FIG.
As shown in FIGS. 7 and 8, the light quantity adjusting device 50 includes a diaphragm blade 53 (a light quantity adjusting blade in the present invention) between a blade retainer 51 and a base plate 52 arranged so as to face each other in the direction of the optical axis 20a. Equivalent) and shutter blades 55 (two sheets) are sandwiched.

  Here, an ND filter 54 that absorbs or reflects a predetermined amount of light passing therethrough is fixed to the diaphragm blade 53. The shutter blade 55 is composed of two thin plates. Furthermore, the blade retainer 51 is formed with an opening 50a for allowing the light beam incident on the second lens group 22 (see FIG. 6) to pass therethrough. Further, the main plate 52 is provided with a rotation center shaft 53a for rotatably supporting the aperture blade 53 and a rotation center shaft 55a for rotatably supporting the shutter blade 55. The diaphragm blades 53 and the shutter blades 55 (two) are rotatably supported by the base plate 52, and are movable between a closed position that closes the opening 50a and an open position that opens the opening 50a.

  Further, the diaphragm blade driving means 56 and the shutter blade driving means 57 are fixed to the base plate 52 by the driving means presser 58. The diaphragm blade driving pin 56a of the diaphragm blade driving means 56 is inserted into the diaphragm blade driving hole 53b of the diaphragm blade 53, and the shutter blade driving pin 57a of the shutter blade driving means 57 is the shutter blade driving hole of the two shutter blades 55. 55b is inserted.

  Accordingly, by driving the diaphragm blade driving means 56, the diaphragm blade 53 moves between a closed position that closes the opening 50a and an open position that opens the opening 50a, and opens and closes the optical fiber by opening and closing the opening 50a. The amount of light passing through the system can be adjusted. Further, by driving the shutter blade driving means 57, each of the two shutter blades 55 moves between a closed position for closing the opening 50a and an open position for opening the opening 50a. Then, by opening and closing the opening 50a with the two shutter blades 55, all of the light rays of the optical system are switched to blocking or passing.

<1. First Embodiment>
[Configuration example of light amount adjustment device in lens barrel]

FIG. 9 is a front view showing a main part of a light amount adjusting device 50 (first embodiment) in a lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. The states of the blade 53 (open) and the shutter blade 55 (open) are shown.
FIG. 10 is a front view showing the main part of the light amount adjusting device 50 (first embodiment) in the lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. The states of the aperture blade 53 (open) and the shutter blade 55 (closed) are shown.
As shown in FIG. 9, in a state where the diaphragm blade 53 has moved to the open position for opening the opening 50a and the shutter blade 55 has also been moved to the open position for opening the opening 50a, the opening 50a is completely opened. Therefore, the second lens group 22 (see FIG. 6) can enter and exit inside the opening 50a.

  Here, since the opening 50a is sufficiently large with respect to the effective light flux range 22b, in the state of the aperture blade 53 (open) and the shutter blade 55 (open) shown in FIG. 9, nothing interferes with the light flux necessary for photographing. Absent. Further, the outer diameter D of the apparatus is determined by the outer shape of the aperture blade 53 at the open position and the outer shape of the two shutter blades 55 at the open position.

On the other hand, as shown in FIG. 10, in the state where the shutter blade 55 has moved to the closing position for closing the opening 50 a, the entire opening 50 a is closed by the two shutter blades 55. Therefore, all the openings 50a are covered, and the light flux in the effective light flux range 22b is completely blocked.
The two shutter blades 55 rotate in conjunction with each other in opposite directions around the respective rotation center shafts 55a.

FIG. 11 is a front view showing a main part of a light amount adjusting device 50 (first embodiment) in a lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. The state of the blade 53 (closed) and the shutter blade 55 (open) is shown.
FIG. 12 is a front view showing the main part of the light amount adjusting device 80 of the reference example, and shows the state of the aperture blade 81 (closed) and the shutter blade 55 (open).
FIG. 13 is a front view showing the main part of the light amount adjustment device 80 of the reference example, and shows the state of the aperture blade 81 (open) and the shutter blade 55 (open).
As shown in FIG. 11, in the state where the diaphragm blade 53 has moved to the closed position that closes the opening 50a, the effective light beam range 22b is entirely covered. Then, the light amount is adjusted by the ND filter 54 positioned so as to overlap the effective light beam range 22b.

  Here, the outer shape of the diaphragm blade 53 is set to the outside of the optical axis with respect to the effective light flux range 22b in the state where the diaphragm blade 53 is in the closed position, and is set to the inside of the opening 50a. In other words, the diaphragm blade 53 covers the entire effective light beam range 22b in the closed position, but leaves a part of the opening 50a outside the effective light beam range 22b (between the outer shape of the diaphragm blade 53 and the opening 50a). The gap 50b is formed).

  Thus, the reason why the outer shape of the diaphragm blade 53 is set inside the opening 50 a is to reduce the outer diameter of the light amount adjusting device 50. This point will be described in detail. When the outer shape of the diaphragm blade 81 is set outside the opening 50a as in the light amount adjusting device 80 of the reference example shown in FIG. Is completely covered by the opening / closing part 81a.

  However, as shown in FIG. 13, when the diaphragm blade 81 is moved to the opening position where the opening 50a is opened, the light amount adjusting device 80 of the reference example is a light amount adjusting device 50 according to the first embodiment (see FIG. 9). ), The opening / closing part 81a of the diaphragm blade 81 protrudes outside. As a result, the light quantity adjusting device 80 (see FIGS. 12 and 13) of the reference example in which the outer shape of the diaphragm blade 81 is set outside the opening 50a is the first in which the outer shape of the diaphragm blade 53 is set inside the opening 50a. The light quantity adjusting device 50 of the embodiment (see FIGS. 11 and 9) is made larger. Therefore, in the light amount adjusting device 50 according to the first embodiment, as shown in FIG. 11, the outer shape of the aperture blade 53 is set inside the opening 50a, and a part of the opening 50a is outside the effective light beam range 22b. Is left (the gap 50b is formed), thereby reducing the radial direction.

  Further, in the light quantity adjusting device 80 of the reference example, as shown in FIG. 13, the opening / closing part 81a remains in the opening 50a even at the opening position of the aperture blade 81. For this reason, even if the diaphragm blade 81 is moved to the open position, there occurs a problem that the diaphragm blade 81 and the second lens group 22 (see FIG. 6) interfere with each other in the opening 50a. It cannot be stored. As a result, it is difficult to reduce the size of the lens barrel 20 in the direction of the optical axis 20a as shown in the lower diagram of FIG.

  Therefore, the light amount adjusting device 50 according to the first embodiment has an outer shape in which a part of the opening 50a is left (a gap 50b is formed) at the closed position of the diaphragm blade 53, whereby the radial direction and the optical axis direction. Is miniaturized. The gap 50 b can be covered with the shutter blade 55.

FIG. 14 is a front view showing a main part of a light amount adjusting device 50 (first embodiment) in a lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. The state of the blades 53 (closed) and the shutter blades 55 (closed) is shown.
As shown in FIG. 14, the outer shape of the shutter blade 55 is set larger than that of the opening 50a in a state where the shutter blade 55 is moved to the closed position where the opening 50a is closed.

  Therefore, by moving the shutter blade 55 to the closed position, the entire opening 50a is covered. As a result, not only the light beam in the effective light beam range 22b is completely blocked, but also the gap 50b (see FIG. 11) that remains even when the diaphragm blade 53 is closed can be covered, and the slight light leaking from the gap 50b can also be blocked. it can.

<2. Second Embodiment>
[Another configuration example of the light amount adjusting device in the lens barrel]

FIG. 15 is a front view showing a main part (second embodiment) of a light amount adjusting device 60 in a lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. The states of the blade 61 (closed) and the shutter blade 55 (open) are shown.
The light amount adjusting device 60 of the second embodiment shown in FIG. 15 is different from the diaphragm blades 53 in the light amount adjusting device 50 of the first embodiment shown in FIG. This is a form in the case of using a diaphragm blade 61 in which a hole) is formed.

  In the light quantity adjusting device 50 of the first embodiment shown in FIG. 11, the aperture hole (not shown) of the aperture blade 53 is formed larger than the effective light beam range 22b. The amount of light passing through the effective light beam range 22b is adjusted only by the ND filter 54 attached so as to close the aperture hole.

  On the other hand, in the light amount adjusting device 60 of the second embodiment shown in FIG. 15, the aperture hole 61a of the aperture blade 61 is formed smaller than the effective light flux range 22b. Therefore, even if the ND filter 54 is not used, the amount of light passing through the effective light beam range 22b is adjusted (squeezed) by the aperture hole 61a by moving the aperture blade 61 to the closed position. However, as shown in the lower diagram of FIG. 15, an ND filter 54 may be attached to close the throttle hole 61a.

<3. Third Embodiment>
[Still another configuration example of the light amount adjusting device in the lens barrel]

FIG. 16 is a front view showing a main part (third embodiment) of a light amount adjusting device 70 in a lens barrel 20 for a digital still camera as an embodiment of the lens barrel of the present invention. The states of the blade 53 (open) and the shutter blade 55 (open) are shown.
The light quantity adjustment device 70 of the third embodiment shown in FIG. 16 is a form in which an opening 70a having a different size is formed with respect to the opening 50a of the light quantity adjustment device 50 of the first embodiment shown in FIG. It is.

  In the light amount adjusting device 50 of the first embodiment shown in FIG. 9, the second lens group 22 (see FIG. 6) entering and exiting the opening 50a is perpendicular to the optical axis 20a with respect to the light amount adjusting device 50 (in the XY directions). It is configured not to move in two orthogonal directions. Therefore, the opening 50a is set so as to maintain a certain clearance that allows entry and exit into the opening 50a with respect to the lens outer diameter 22a (see FIG. 6) of the second lens group 22.

  On the other hand, in the light amount adjustment device 70 of the third embodiment shown in FIG. 16, the image blur correction lens 26 moves in the XY direction with respect to the light amount adjustment device 50 (see FIG. 9) so as to realize a camera shake prevention function. This is a configuration in the case of. Specifically, the image blur correction lens 26 can move in two directions (XY directions) orthogonal to each other on a plane perpendicular to the optical axis with respect to a moving frame (not shown) that holds the image blur correction lens 26. Is held in. Therefore, the camera shake prevention function is realized by moving the image blur correction lens 26 in a direction opposite to the direction of camera shake.

  Therefore, the opening 70a is set so as to maintain a predetermined clearance with respect to the envelope during the full stroke operation of the image blur correction lens 26 in the XY direction. Therefore, regardless of the movement position of the image blur correction lens 26 in the X and Y directions, the optical axis direction of the image blur correction lens 26 that is moved by a moving frame (not shown) can enter and exit the opening 70a.

  Here, the clearance between the opening 70a and the image blur correction lens 26 is set to be the same (required minimum) as in the case of the light amount adjustment device 50 of the first embodiment shown in FIG. Therefore, the opening 70a needs to be formed larger than the opening 50a by the amount of movement of the image blur correction lens 26 in the XY direction. As a result, there is a concern that the device outer diameter D of the light amount adjusting device 70 is increased.

  However, the light amount adjusting device 70 of the third embodiment shown in FIG. 16 also leaves a part of the opening 70a at the closed position of the aperture blade 53 (a gap similar to the gap 50b shown in FIG. 11 is formed). Since it has an outer shape, it is possible to reduce the size in the radial direction. Therefore, the light amount adjusting device 70 that moves the image blur correction lens 26 in and out of the opening 70a can prevent the camera shake from being prevented and further increase in size due to the addition of the camera shake prevention function.

<4. Fourth Embodiment>
[Still another example of configuration of light amount adjusting device in lens barrel]

FIG. 17 is a cross-sectional view showing a peripheral portion (fourth embodiment) of a light amount adjusting device 90 in a lens barrel 320 for a digital still camera as an embodiment of the lens barrel of the present invention.
The fourth embodiment shown in FIG. 17 is different from the other embodiments in that a cam pin 91 is provided in the light amount adjusting device 90.

  Specifically, the movement of the second lens group 22 in the direction of the optical axis 20a shown in FIG. 6 is performed by the cam pin 39 and the rotary ring 36 (see FIG. 2) provided on the second moving frame 34 that holds the second lens group 22. This is realized by mutual rotation of the rotating ring 36 and the second moving frame 34.

  However, as in the fourth embodiment shown in FIG. 17, the cam pin 91 may be provided not on the second moving frame 34 but on the light amount adjusting device 90. In this case, the second lens group 22 retracts from the opening 90a of the light amount adjusting device 90 and moves in the direction of the optical axis 20a together with the light amount adjusting device 90. That is, the movement of the second lens group 22 in the direction of the optical axis 20a is caused by engaging the cam pin 91 provided in the light amount adjusting device 90 with the cam groove provided in the rotary ring 36 (see FIG. 2). And the light quantity adjusting device 90 are realized by mutual rotation.

As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, The following various deformation | transformation are possible. For example,
(1) 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 devices such as digital video cameras and camera-equipped mobile phones.

  (2) In the embodiment, the first moving frame 33 and the second moving frame 34 are moved by the rotation of the rotating ring 36. The rotating ring 36 rotates around the optical axis 20a and the optical axis 20a. Move in the direction. However, the axis of rotation center of the rotating ring may not coincide with the optical axis, and the rotating ring may not move in the optical axis direction.

  (3) In the embodiment, an opening 50a is formed in the blade retainer 51, and the second lens group 22 enters and exits the opening 50a. The opening is located at the blade retainer 51, the base plate 52, and the open position. The two shutter blades 55 and the aperture blade 53 may be determined by a combination of the inner peripheral shapes. For example, the inner periphery of the opening when viewed from the direction of the optical axis 20a is configured by the inner periphery of the blade retainer and a part of the inner periphery of the shutter blade, and the optical lens enters and exits the opening. To do.

  (4) In the embodiment, the outer shape of the two shutter blades 55 located at the closed position is made larger than the opening 50a so as to completely cover the gap 50b. However, although the shutter blade is larger than the effective light beam range 22b, the outer shape may be smaller than the opening 50a, and the gap 50b may be left.

  (5) In the embodiment, the relative movement of the second lens group 22 and the light amount adjusting device 50 in the direction of the optical axis 20a is realized by the bias of the spring 25 and the pressing by the rear barrel 38 of the light amount adjusting device 50. Yes. However, the second moving frame 34 that holds the second lens group 22 and the light amount adjusting device 50 are each formed with a cam pin that engages with a cam groove having a different locus provided on the rotating ring 36. The relative movement of the second lens group 22 and the light amount adjusting device 50 in the optical axis direction may be realized by mutual rotation. Further, an actuator such as a motor and its control means may be provided to realize relative movement of the second lens group 22 and the light amount adjusting device 50 in the optical axis direction.

  (6) In the embodiment, the light amount adjusting device 50 is located on the image pickup element 24 side of the second lens group 22, and the relative movement of the second lens group 22 and the light amount adjusting device 50 in the optical axis 20a direction is a spring. 25 and the pressing by the rear barrel 38 of the light amount adjusting device 50 are realized. However, the light amount adjusting device 50 may be located on the subject side of the second lens group 22. In this case, the relative movement of the second lens group 22 and the light amount adjusting device 50 in the optical axis direction is caused by the bias of the spring 25 and the second lens group 22 such as the first moving frame 33 of the light amount adjusting device 50. It can be realized by pressing by a moving member on the side. As described above, the second moving frame 34 that holds the second lens group 22 and the light amount adjusting device 50 are each formed with cam pins that engage with cam grooves having different loci provided in the rotary ring 36, and rotate. The relative movement of the second lens group 22 and the light amount adjusting device 50 in the optical axis direction may be realized by mutual rotation with the ring 36. Further, an actuator such as a motor and its control means may be provided to realize relative movement of the second lens group 22 and the light amount adjusting device 50 in the optical axis direction.

  (7) In the embodiment, the shutter blade 55 that closes the opening 50a of the light amount adjusting device 50 is composed of two sheets, but may be composed of one sheet or three or more sheets.

  (8) In the light quantity adjusting device 50 of the embodiment, the aperture hole (not shown) of the aperture blade 53 is formed larger than the effective light beam range 22b, and the ND filter 54 is attached so as to close the aperture hole, Adjustment of the amount of light passing through the effective light beam range 22b is realized only by the ND filter 54. However, the diaphragm blade itself may be formed of an ND filter that does not have a through hole that includes at least a part of the effective light beam range 22b on the inside. In this case, the light amount passing through the effective light beam range 22b can be adjusted by the ND filter. Realized.

10 Digital still camera (imaging device)
20 lens barrel 20a optical axis 21 first lens group 22 second lens group (imaging lens)
22a Lens outer diameter 22b Effective luminous flux range 34 Second moving frame (holding frame)
50 Light quantity adjustment device 50a Opening 50b Clearance 53 Aperture blade (light quantity adjustment blade)
55 Shutter blade 60 Light intensity adjustment device 61 Aperture blade (light intensity adjustment blade)
61a Aperture hole (through hole)
70 light amount adjusting device 70a opening 90 light amount adjusting device 90a opening 320 lens barrel

Claims (5)

An optical lens forming at least part of the imaging optical system;
A holding frame for holding the optical lens;
A light amount adjustment device that adjusts the amount of light reaching an effective imaging range on the imaging plane,
The light amount adjusting device is:
Supported so as to be relatively movable in the optical axis direction with respect to the optical lens,
An aperture formed to allow the light beam incident on the optical lens to pass therethrough and to allow at least a part of the optical lens to enter and exit in the optical axis direction;
A light amount adjusting blade provided movably between a closed position that enters the opening and an open position that retreats from the opening;
The light amount adjusting blade is located outside the effective light beam range at the closed position when a cross section of the opening of the light beam that passes through the opening and forms an image in an effective imaging range on the imaging plane is an effective light beam range. The lens barrel is configured such that at least a part of the optical lens can enter and exit in the optical axis direction inside the opening at the open position. The lens barrel according to claim 1,
The light amount adjusting device has a shutter blade provided movably between a closed position that enters the opening and an open position that retreats from the opening,
The shutter blade is configured to close all of the opening at the closing position of the shutter blade, and at the opening position of the shutter blade, at least a part of the optical lens is disposed in the optical axis direction inside the opening. A lens barrel configured to be able to enter and exit. The lens barrel according to claim 1,
The optical lens is provided to be movable in two directions perpendicular to each other on a plane perpendicular to the optical axis of the optical lens,
The opening is formed so that at least a part of the optical lens can enter and exit in the optical axis direction regardless of the movement positions in two directions perpendicular to each other on a plane perpendicular to the optical axis of the optical lens. . The lens barrel according to claim 1,
The light quantity adjusting blade is
A thin plate having a through hole containing at least a part of the effective light flux range on the inside;
A lens barrel configured by an ND filter covering the through hole. An optical lens forming at least part of the imaging optical system;
A holding frame for holding the optical lens;
A light amount adjustment device that adjusts the amount of light reaching an effective imaging range on the imaging plane,
The light amount adjusting device is:
Supported so as to be relatively movable in the optical axis direction with respect to the optical lens,
An aperture formed to allow the light beam incident on the optical lens to pass therethrough and to allow at least a part of the optical lens to enter and exit in the optical axis direction;
A light amount adjusting blade provided movably between a closed position that enters the opening and an open position that retreats from the opening;
The light amount adjusting blade is located outside the effective light beam range at the closed position when a cross section of the opening of the light beam that passes through the opening and forms an image in an effective imaging range on the imaging plane is an effective light beam range. The imaging device is configured such that at least a part of the optical lens can enter and exit in the optical axis direction inside the opening at the open position.

Images