JP2000310803A - Light quantity adjusting device, lens barrel and photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a light quantity adjusting device capable of performing consecutive light quantity adjustment and shutter operation, preventing the deterioration of optical performance with small limited light quantity and coping with both the photography of a moving picture and the photography of a still picture without increasing the number of parts and making the device larger. SOLUTION: This light quantity adjusting device is provided with a light shielding member moving between an opened state and a closed state so as to perform at least either the consecutive light quantity adjustment or the shutter operation, a 1st actuator 27 driving the light shielding member, a light quantity limiting member 25 where an aperture having smaller area than opening area obtained in a state where the light shielding member is opened is formed, a 2nd actuator 29 driving the member 25, and a dimming filter 26 attached to at least either the member 25 or the light shielding member and covering over the aperture of the member 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light amount adjusting device disposed in a lens barrel used for a photographing device such as a camera, a video camera, a digital still camera and the like.

[0002]

2. Description of the Related Art A video camera such as a video camera includes:
A moving image light amount adjusting device that can continuously change the aperture from an open state to a fully closed state is used. On the other hand, a still image photographing camera such as a digital still camera may use a still image light amount adjusting device capable of switching between an open state and a small aperture state (for example, F8) at two positions and also capable of performing a shutter operation. .

[0003]

However, in the conventional light amount adjusting device, a small aperture frame for switching between an open state and a small aperture state, an actuator for driving the small aperture frame, a blade for performing a shutter operation, and the blade are driven. Since the number of components such as actuators is increased, there is a disadvantage that the entire device becomes large.

If the aperture diameter of the small stop frame is made smaller than a certain size, the optical performance (resolution) is degraded due to the light diffraction phenomenon, so that the minimum value of the aperture diameter is limited. For this reason, just switching the small aperture frame in and out
There is also a disadvantage that the light quantity cannot be sufficiently adjusted.

Accordingly, an object of the present invention is to realize a compact light amount adjusting device capable of sufficiently adjusting the light amount.

[0006]

In order to achieve the above object, the light amount adjusting device of the present invention moves from an open state to a closed state to perform at least one of continuous light amount adjustment and shutter operation. A light-blocking member, a first actuator that drives the light-blocking member, a light-amount limiting member having an opening smaller than the opening area of the light-blocking member in an open state, and a second actuator that drives the light-amount limiting member And a neutral density filter attached to at least one of the light quantity limiting member and the light blocking member, and covering the opening of the light quantity limiting member.

As a result, the light amount can be continuously adjusted without increasing the number of components and without increasing the size of the apparatus, and it is possible to prevent the deterioration of the optical performance with a small amount of light.

If a dimming filter is attached to both the light quantity limiting member and the light shielding member, it becomes possible to perform at least one more level of light quantity adjustment with a small light quantity as compared with a case where a dimming filter is attached to only one of them. .

When the light amount adjusting device is mounted on a lens holding member in a lens barrel, the light shielding member and the light amount limiting member are arranged at an end of the lens holding member on the object side, and a first actuator and a second actuator are provided. Are disposed closer to the image plane than the light blocking member and the light amount limiting member, and further, the first actuator and the second actuator are disposed in a range where the lens moving mechanism is not disposed when viewed in the optical axis direction. By effectively utilizing the space in the lens barrel, it is possible to prevent the lens barrel from increasing in size.

[0010]

1 to 6 show an aperture / shutter device (light amount adjusting device) according to an embodiment of the present invention.

FIG. 6A is a sectional view of a zoom lens barrel in which an aperture / shutter device is incorporated. In addition,
This zoom lens barrel is used in a photographing apparatus capable of photographing moving images and still images.

In FIG. 1, reference numeral 1 denotes a front barrel, 2 denotes a flat glass fixed to the front end of the front barrel 1, 3 denotes a first-group optical system, and 4 denotes a first-group optical system. The first group moving frame that can move in the axial direction, 5 is the aperture shutter device of the present embodiment, 6
Is a two-group optical system, 7 is a second-group moving frame that holds the second-group optical axis and is movable in the optical axis direction, 8 is a third-group optical system that is held at the rear end of a rear barrel 9, and 9 is Rear barrels 10, 10 connected to the rear end of the front barrel 1 are first and second group moving frames 4, 7, respectively.
And a guide bar for guiding the moving frames 4 and 7 in the optical axis direction and preventing rotation of the moving frames 4 and 7.

The flat glass 2 is fixed to the front lens barrel 1,
Protects moving internal parts. The first-group optical system 3 is a focusing lens for adjusting focus, and is attached to the first-group moving frame 4. The sleeve portion 4a and the U groove portion 4b of the first group moving frame 4 are fitted to the guide bars 10 and 11 so as to be able to move in parallel with the optical axis. This one group moving frame 4
Is driven in the optical axis direction by a driving unit (not shown) such as a step motor. The aperture shutter device 5 is located immediately before the second-group optical system 6, and is fixed to the second-group moving frame 7 with screws or the like. The second group optical system 6 is a zooming lens for zooming, and the sleeve part 7a and the U groove part 7b of the second group moving frame 7 are fitted to the guide bars 11 and 10 so as to be able to move in parallel with the optical axis. ing. The second group moving frame is driven in the optical axis direction together with the diaphragm shutter device 5 by driving means (not shown) (for example, a step motor having a lead screw engaged with the second group moving frame 7 as an output shaft). The third group optical system 8 is fixed to the rear barrel 9.

FIG. 6A shows a state in which the focal length is wide. In this state, the first group moving frame 4 and the second group moving frame 7 are apart from each other.

FIG. 6B shows a state in which the focal length is telephoto, and the first group moving frame 4 and the second group moving frame 7 are close to each other.

The graph shown in FIG. 6C shows the movement of the first-group moving frame 4 and the second-group moving frame 7 during the zoom operation, and the zoom operation for changing the focal length from wide to tele is performed. And the first group moving frame 4 and the second group moving frame 7 move in the optical axis direction along the guide bars 10 and 11, respectively, so as to trace above. As a result, the focal length of the zoom lens barrel changes.

Here, considering that the first-group moving frame 4 and the second-group moving frame 7 move as shown in FIGS. 6A and 6B, the actuator light for driving the diaphragm / shutter device 5 is used. The space between the second group optical system 6 and the third group optical system 8 is considered to be most effective as the axial arrangement space. Therefore, the actuator of the aperture / shutter device 5 should be arranged closer to the image plane than the positions of the small aperture frame and the shutter (aperture) blade.

Next, FIGS. 1 to 5 show the structure of the aperture / shutter device 5 described above. In these figures, 21 is a base, 22 is a light-shielding blade A swingable about a shaft 21a provided on the base 21, and 23 is a light-shielding blade B swingable about a shaft 21b provided on the base 21. , 24 are partitioning blades, 25 is a shaft 2 provided in the base 21 and having an inner diameter opening smaller than the open opening 21f formed in the base 21.
1c small aperture frame (light quantity limiting member) swingable about 2c, 2
Reference numeral 6 denotes an ND filter (light reduction filter) that covers the circular opening of the small stop frame 25, and reference numeral 32 denotes a pressing plate.

Further, 27 is a blade actuator, 2
Reference numeral 8 denotes an interlocking arm for a blade, 29 denotes an actuator for a small aperture frame, and 30 denotes an interlocking arm 30 for a small aperture frame, each of which is attached to the base 21.

The base 21 has a rail 21 for the blade A.
d, blade 21e for blade B, hole 21g for screwing diaphragm / shutter device 5 to second lens barrel 7, blade A22
Stopper 21h, blade B23 in the closed position of
The mechanical stopper 21i at the closed position is formed. Reference numeral 31 denotes a driving amount detection sensor (a hall element or the like) of the blade interlocking arm 28.

FIG. 1A shows that a blade 21 is attached to a base 21.
The figure shows a state in which only is incorporated. In FIG. 1B,
This shows a state in which the blade A22 and the blade B23 are assembled into the base 21, and the blades A and B are open and open. FIG. 1C shows a closed state. The open / close shutter operation can be performed by moving the blade interlocking arm 28 shown in FIG. 4 between both ends of the angle θ by the blade actuator 27. Further, since the drive amount of the blade interlocking arm 28 can be detected by the drive amount detection sensor 31, a shutter operation from an opening diameter smaller than the open opening 21f is also possible. That is, the shutter speed can be changed.

Furthermore, the aperture diameter can be set to an arbitrary size, and continuous aperture diameter control, that is, a moving picture diaphragm operation can be performed.

FIG. 2A shows a state where the partitioning blades 24 are further assembled from the assembled state shown in FIG. 1B. The partitioning blades 24 are arranged between the movable blades A22 and B23 and the movable small aperture frame 25 in order to prevent interference between them.

FIG. 3A shows a state in which the small aperture frame 25 is further assembled from the assembled state shown in FIG. 2A, and the small aperture frame 25 is out of the open opening 21f. Is shown. FIG. 3B shows a small aperture frame 25.
Indicates an in-state covering the open opening 21f.

When the interlocking arm 30 for the small aperture frame moves between the two mechanical ends at the angle Δ shown in FIG. 4, the small aperture frame 25 is swung to switch between the out state and the in state. it can. The circular aperture formed in the small aperture frame 25 has an opening diameter that does not deteriorate the optical performance (resolution) of the photographing optical system (for example, corresponds to F8).
An ND filter 26 is attached to the small aperture frame 25 so as to cover the entire circular opening.

In consideration of FIGS. 4, 5, and 6, when the arrangement space is considered in the optical axis direction of the actuator of the diaphragm / shutter device 5 (in the direction of arrow S), the guide bars 10, 11, A mechanism for moving the moving frames 4, 7 in the optical axis direction, such as the sleeve 4a, the U-groove 4b, the sleeve 7a, the U-groove 7b, and the driving means of the second moving frame 7, is disposed. Is considered the most effective.

Therefore, the actuators 27 and 29
In FIG. 1, the first group optical system 3 and the second group optical system 6 are disposed on the left and right sides of the moving mechanism of the first group optical system 3 and the second group optical system 6, and are arranged outside the optical system holding cylinder portion 7c of the second group moving frame 7. Should.

Thus, the first group optical system 3 and the second group optical system 6
And a close-up state (telescopic state) in the optical axis direction can be realized, and the space in the lens barrel can be effectively used to reduce the size of the entire lens barrel.

A second ND filter having a diameter equivalent to F8 is attached to one of the blades A22 and B23, and the small iris frame 25 is inserted into the optical path of the second ND filter. If you take in and out, you can adjust the light amount even wider.

[0030]

As described above, according to the present invention,
A light-shielding member that performs at least one of continuous light amount adjustment and shutter operation, and a first light-shielding member that drives the light-shielding member.
An actuator, a light amount limiting member having an opening having an area smaller than an opening area of the light shielding member in an open state, a second actuator for driving the light amount limiting member, and at least one of the light amount limiting member and the light shielding member And a light-attenuating filter that covers the opening of the light-amount limiting member, so that the light-amount adjusting device is configured. Therefore, the light amount can be continuously adjusted without increasing the number of parts and without increasing the size of the device. In addition, it is possible to realize a light amount adjusting device capable of performing both moving image shooting and still image shooting, which can perform the shutter operation and the shutter operation, and can prevent the deterioration of the optical performance with a small limited light amount.

If a dimming filter is attached to both the light quantity limiting member and the light blocking member, at least one more level of light quantity adjustment with a small light quantity can be performed as compared with a case where a dimming filter is attached to only one of them.

When the light amount adjusting device is mounted on the lens holding member in the lens barrel, the light shielding member and the light amount limiting member are arranged at the end of the lens holding member on the object side, and the first and second actuators are provided. Is disposed closer to the image plane than the light blocking member and the light amount limiting member, and the first actuator and the second actuator are disposed in a range where the lens moving mechanism is not disposed in the optical axis direction view. By effectively utilizing the space in the cylinder, the enlargement of the lens barrel can be prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the assembly and operation of an aperture / shutter device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of assembly and operation of the aperture / shutter device.

FIG. 3 is an explanatory diagram of assembly and operation of the aperture / shutter device.

FIG. 4 is an explanatory diagram of a base and an actuator of the diaphragm / shutter device.

FIG. 5 is a partially enlarged view of a lens barrel in which the above-described aperture / shutter device is incorporated.

FIG. 6 is an overall sectional view and an operation explanatory view of the lens barrel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Front lens barrel 2 ... Flat glass 3 ... 1st group optical system 4 ... 1st group moving frame 5 ... Aperture / shutter device 6 ... 2nd group optical system 7 ... 2nd group moving frame 8 ... 3rd group optical system 9 ... Rear mirror Cylinders 10, 11 Guide bar 21 Base 22 Blade A 23 Blade B 24 Partitioning blade 25 Small aperture frame 26 ND filter 27 Blade actuator 28 ... Blade interlocking arm 29 ... Small aperture frame actuator 30 ... Synchronizing arm for small aperture frame 31 ... Drive amount detection sensor 32 ... Presser plate

Claims (8)

[Claims] A light-shielding member that moves between an open state and a closed state to perform at least one of continuous light amount adjustment and shutter operation; a first actuator that drives the light-shielding member; A light amount limiting member formed with an opening having an area smaller than the opening area in the open state, a second actuator for driving the light amount limiting member, and at least one of the light blocking member and the small light amount limiting member. And a neutral density filter that covers an opening of the light quantity limiting member. 2. The light amount adjusting device according to claim 1, further comprising a detecting unit for detecting a moving state of the light shielding member. 3. A lens barrel comprising the light amount adjusting device according to claim 1. 4. The lens barrel according to claim 3, further comprising a lens holding member movable in an optical axis direction, wherein the light amount adjusting device is attached to the lens holding member. 5. The light-shielding member and the small-light-amount limiting member are arranged at a subject-side end of the lens holding member,
The lens barrel according to claim 4, wherein the first actuator and the second actuator are arranged closer to an image plane than the light blocking member and the small light amount limiting member. 6. A mechanism for moving a lens in an optical axis direction, wherein the first actuator and the second actuator are arranged in a range where the moving mechanism is not arranged in the optical axis direction. The lens barrel according to claim 4, wherein: 7. The first actuator and the second actuator
7. The lens barrel according to claim 5, wherein an actuator is disposed outside a cylindrical portion of the lens holding member to which the lens is attached. 8. A photographing apparatus comprising the lens barrel according to claim 3.