JP2004252367A - Light quantity adjusting device and camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light quantity adjusting device which has a proper arrangement of light blocking blades and a small difference in light blocking quantity between the light blocking blades, enables proper exposure, and can be made small. <P>SOLUTION: In a lens barrel 10 which has the light quantity adjusting device, a one-group frame 19 and a two-group frame 20 are provided as a photography optical system which moves forward and backward relatively in the optical axis O in collapse driving and zoom driving, and a shutter unit 21 is arranged on the back side of the two-group frame 20 integrally with the two-group frame 20. The shutter unit 21 has shutter blades 49 and 50 and an ND filter 51 inside and they are arranged not at the optical stop position of the photography optical system. At the arrangement positions of the shutter blades 49 and 50, ambient light is biased, and shading is easy to occur in high-luminance photography and high-speed-shutter photography, specially, wide-angle photography. For prevention against the shading, sensitivity adjustment is made possible and further switching to a lower shutter speed is enabled. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light amount adjusting device arranged in an optical path of an optical system and a camera incorporating the light amount adjusting device.
[0002]
[Prior art]
Conventionally, in a light amount adjusting device such as a general shutter device, the light amount is adjusted by opening and closing a plurality of light shielding blades. For example, Patent Literature 1 discloses a shutter device that opens and closes by rotationally driving two light shielding blades in opposite directions. The shutter device described in Patent Document 2 discloses a shutter device that opens and closes by driving a plurality of light-shielding blades.
[0003]
In addition, there has been proposed a filter that adjusts the amount of light by inserting and removing an ND filter in an optical path. For example, Patent Document 3 discloses a digital camera that incorporates a dimming device (light amount adjusting device) that inserts the ND filter into an opening when the subject luminance is equal to or more than a predetermined value.
[0004]
[Patent Document 1]
Patent Document 1 is JP-A-2002-287207.
[0005]
[Patent Document 2]
Patent Document 2 is JP-A-2000-89295.
[0006]
[Patent Document 3]
Patent Document 3 is JP-A-2000-152072.
[0007]
[Problems to be solved by the invention]
In the above-described conventional shutter device, the light-shielding blade is often arranged at a so-called aperture position of an optical system in which both the central light beam and the peripheral light beam are distributed without being deviated from the optical axis O. However, in order to dispose the shutter device (light amount adjusting device) at the stop position, a space for disposing the shutter device is naturally required at the stop position. Therefore, various restrictions are imposed on the arrangement, movement position, shape, and the like of the optical system and various mechanisms in the lens barrel, and it has been difficult to provide a more compact device.
[0008]
However, simply moving the light-shielding blade to a position different from the optical stop position causes the peripheral light beam to be deviated with respect to the optical axis O, so that the peripheral light beam and the central light beam are blocked during opening and closing of the light-shielding blade. The state is different, and shading occurs due to a light amount difference between the peripheral portion and the central portion. Further, depending on the behavior of the light-shielding blade, shading due to the light amount difference in each quadrant may occur even in the peripheral portion. Such a tendency becomes remarkable especially when a short focal length side (wide side) or a high shutter speed is used.
[0009]
The present invention has been made in view of the above-described problems, and has an appropriate arrangement of the light-shielding blades, and furthermore, the light-shielding blades are less likely to generate a light-shielding light amount difference, and can perform more appropriate exposure, and It is an object of the present invention to provide a light amount adjusting device or a camera that can be reduced in size.
[0010]
[Means for Solving the Problems]
The light amount adjusting device according to claim 1 of the present invention is a light amount adjusting device arranged in an optical path of an optical system, wherein an optical element forming a part of the optical system with respect to an optical stop position of the optical system. A pair of light-shielding blades disposed on opposite sides of the light-shielding member, and a driving unit for opening and closing the opening by rotating the pair of light-shielding blades in directions opposite to each other. The blade is driven to open and close.
[0011]
In the light amount adjusting device according to a second aspect of the present invention, in the light amount adjusting device according to the first aspect, each of the light-shielding blades substantially uniformly shields a peripheral light beam of the optical system when opening and closing the light-shielding blade.
[0012]
The light amount adjusting device according to claim 3 of the present invention includes a lens having an optical surface protruding from an optical stop position, a light shielding blade disposed on a side of the lens opposite to the optical surface, and the light shielding blade. And a driving source for driving, the driving source being arranged on a side of the lens.
[0013]
According to a fourth aspect of the present invention, in the light quantity adjusting device according to the third aspect, the driving source is disposed in a space between the optical stop position and the light shielding blade in an optical axis direction. You.
[0014]
The camera according to claim 5 of the present invention is arranged on the opposite side of an optical stop position of the optical system with an optical element constituting a part of the optical system therebetween, and has an exposure opening of the optical system. A shutter device having a light-shielding blade movable between an opening position and a shielding position, and a shutter device disposed in an optical path of the optical system and movable to a position to open and cover the exposure opening, A filter having a transmittance, and control means for determining whether or not to move to the position covering the filter in accordance with a zoom state and a shutter speed of the optical system, wherein the filter is located at the position where the filter is opened. In a certain state, when the shutter speed is higher than a predetermined value, an image is taken at a lower shutter speed as a position for covering the filter.
[0015]
The camera according to claim 6 of the present invention includes a first lens group having a concave exit surface, and a second lens group having a convex surface on which light emitted from the first lens group is incident. A variable-magnification optical system having an optical stop position located between the first lens group and the second lens group, and an optical system disposed behind the second lens group, A shutter device having a light-blocking blade movable between a position where the opening is opened and a position where the opening is blocked, and a shutter device which is disposed behind the second lens group and is movable between a position where the exposed opening is opened and a position where the exposed opening is covered. A filter device having a filter having a predetermined transmittance, and control means for determining whether to move to the position covering the filter according to the zoom state and shutter speed of the optical system, With the filter in the open position, If the serial shutter speed is faster than the predetermined value, the filter was moved into a position covering above is taken using a slower shutter speed.
[0016]
According to a seventh aspect of the present invention, in the camera according to the fifth or sixth aspect, the control means determines that a shutter speed at the time of shooting is equal to or more than a predetermined value in a state where the filter is at the open position. If so, the filter is controlled to move to the position where the filter is covered, and the predetermined value of the shutter speed is controlled to adopt a different value depending on the focal length of the optical system.
[0017]
The camera according to an eighth aspect of the present invention is the camera according to the seventh aspect, wherein the predetermined value of the shutter speed when the optical system is on the short focal length side is determined when the optical system is on the long focal length side. Is higher than the predetermined value of the shutter speed.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are perspective views showing the appearance of a camera incorporating a lens barrel having a light amount adjusting device according to one embodiment of the present invention. FIG. 1 shows a barrier closed state, and FIG. The state is shown. FIG. 3 is a diagram showing an appearance of a lens barrel incorporated in the camera in an extended state.
[0019]
In the following description, the front and rear (subject side and imaging side) directions along the photographing lens optical axis O are defined as a Z direction, a horizontal direction perpendicular to the Z direction is defined as an X direction, and a vertical direction perpendicular to the Z direction is defined as Y direction. Direction. The rotation direction is indicated by the rotation direction as viewed from the front subject side.
[0020]
The camera 1 is a digital camera capable of converting an image signal of a subject captured by an image sensor into a digital signal and recording the digital signal on a memory card or the like. As shown in FIGS. 1 and 2, the exterior body of the camera 1 includes a front cover 2, a middle cover 3, and a rear cover 4. The front cover 2 has a photographic lens barrel 10, a finder window on its front. A slidable lens barrier 5 for opening and closing the front surface such as 6 is disposed.
[0021]
The front cover 2, the middle cover 3, and the rear cover 4 are formed of a thin metal plate serving as an exterior member forming an appearance surface, and each of the inner frames is formed of a synthetic resin for reinforcement and assembly. The member is adhesively fixed.
[0022]
On the front cover 2, a photographing lens barrel (hereinafter, referred to as a lens barrel) 10, which is a retractable zoom lens barrel, a finder window 6, a strobe light emission window 7, and the like are disposed on the front surface thereof. . Front portions of the lens barrel 10, the finder window 6, the strobe light emission window 7, and the like are opened and closed by a slidable lens barrier 5. When the lens barrier is in the closed position on the right side, the lens barrel is retracted to the retracted position, and the front part is closed to make it impossible to take a picture (FIG. 1). When in the left open position, the front surface of the lens barrel is opened, and the lens barrel is extended to a position where photographing is possible (FIG. 2).
[0023]
Further, a release switch operation button 8 is disposed on an upper surface of the middle cover 3, and a finder eyepiece window 9 is disposed on an upper rear surface of the rear cover 4.
[0024]
The lens barrel 10 is a collapsible zoom lens barrel having a lens barrel. As shown in FIG. 3, a fixed frame 11 fixedly supported inside the camera 1 and the fixed frame 11 rotate and move back and forth. It has a cam frame 15 and a zoom frame 16 that are freely supported and are extended outward from the fixed frame 11 in a shooting state. In the cam frame 15 and the zoom frame 16, a first group lens 47 and a second group lens 48 (FIG. 5) constituting a zoom photographing optical system are incorporated. The front end of the fixed frame 11 is supported by a lens barrel holding frame 71 mounted on the front cover 2. Further, a flexible printed circuit board (hereinafter, referred to as FPC) 109 for shutter drive control and focus drive control is derived from the fixed frame 11, and further, from a zoom drive unit 13 mounted on the fixed frame 11, The zoom drive control FPC 108 is derived. These FPCs are connected to a control unit (not shown) inside the camera. Hereinafter, details of the structure of the lens barrel 10 will be described.
[0025]
FIG. 4 is an exploded perspective view of components on the fixed frame side of the lens barrel seen from the subject side, and FIG. 5 is an exploded perspective view of components of the lens barrel on the cam frame side seen from the subject side. is there. FIG. 6 is an enlarged exploded perspective view of the second group frame and the shutter unit in the lens barrel as viewed from the subject side. FIG. 7 is an exploded perspective view of the focusing drive unit, the integrated second group frame and the shutter unit in the lens barrel, as viewed from the image forming side. 8 to 10 are views showing the upper half of a longitudinal section in each state of the lens barrel. FIG. 8 shows a retracted state, FIG. 9 shows a wide state, and FIG. 10 shows a tele state. .
[0026]
As shown in FIGS. 4 and 5 and the like, the main configuration of the lens barrel 10 is mainly a fixed frame 11 fixedly supported on the camera body, and a zoom having a zoom motor 24 attached to an outer peripheral portion of the fixed frame 11. A drive unit 13, a CCD unit 12 having a built-in CCD as an image pickup device fixed to the rear side of the fixed frame 11, a float key 14 for guiding a zoom frame 16 and a second group frame 20 described later in a straight line, and a fixed A cam frame 15 that fits into the frame 11 and moves forward and backward while rotating between the retracted position and the photographing position, and rotates between the wide rotation position and the tele-rotation position at the above-described photographing position. The zoom frame 16 is fitted freely, is guided linearly by the float key 14, and moves forward and backward between the retracted position and the photographing position, and the focusing drive frame 18 as the first frame fixed in the zoom frame 16 and the third frame. Frame A focusing drive frame unit 17 composed of a certain first group frame 19, supported in the cam frame 15 so as to be able to move forward and backward, and a second group frame 20 as a second frame, fixedly supported by the second group frame 20, and capable of opening and closing. A shutter unit 21 as a light amount adjusting device (shutter device) having the shutter blades 49 and 50 and the ND filter 51, and a first-group lens which constitutes a photographic optical system and is a focusing lens held by the first-group frame 19 47, a second lens group 48 held by the second group frame 20, a light-shielding rubber 72 disposed between the front end of the zoom frame 16 and the front end of the first group frame 19, and the front end of the cam frame 15 and the zoom. A light-shielding rubber 73 arranged between the outer periphery of a metal tube 32 (described later) of the frame 16, a light-shielding rubber 74 arranged between the distal end of the fixed frame 11 and the outer periphery of the metal tube 31 (described later) of the cam frame 15, Arranged on the back of the shutter unit 21 Comprising a light-shielding sheet 55 is a light shielding member made of a flexible sheet member.
[0027]
The fixed frame 11 is an annular member having an opening 11a, and a gear chamber 11d is provided on an outer peripheral portion thereof. In the gear chamber 11d, a long gear 26 for rotating and driving the cam frame 15 has an axial center. Are rotatably supported in a state along the Z direction. The fixed frame 11 has a female helicoid screw 11b on its inner peripheral portion, a lock groove 11c along the circumferential direction communicating with the female helicoid screw 11b, and key grooves 11f and 11g along the Z direction. Provided. Further, a cam frame rotation position detection sensor (not shown) for detecting the position of the mirror portion 15f for detecting the position near the collapsed rotation end of the cam frame 15 is arranged on the inner peripheral portion.
[0028]
The zoom drive unit 13 includes a gear box 23 containing a reduction gear train and a final-stage idle gear 25, and a zoom motor 24 which is a DC motor for zoom drive with an encoder. The zoom drive unit 13 is fixed to the outer peripheral portion of the fixed frame 11 by screwing a screw inserted through the screw insertion holes 23 a and 23 b of the gear box 23 into a screw screw hole 11 e or the like at the end of the long gear chamber of the fixed frame 11. You. In the fixed state, the idle gear 25 meshes with the long gear 26. The long gear 26 also meshes with a zoom finder driving gear 75 (not shown), and also transmits a driving force for driving the zoom of the finder optical system.
[0029]
The CCD unit 12 includes a CCD holder 22 having an imaging opening 22a and a long gear shaft support hole 22b, a low-pass filter 61 disposed inside the opening 22a, and a CCD substrate 63 fixed to the back surface of the CCD holder 12. And a CCD 62 mounted on the CCD substrate 63 and arranged so that the imaging surface is orthogonal to the optical axis O, and a CCD positioning plate 64 for positioning the CCD 62 with respect to the CCD holder 12. Note that a CCD rubber 65 is sandwiched between the low-pass filter 61 and the CCD 62 in a compressed state.
[0030]
The float key 14 is a ring member made of a metal plate, has an opening portion 14a, and has two key portions 14d and 14f extending in a state parallel to the Z direction toward the front, and protruding to the outer periphery and fixed. Two convex portions 14b and 14c are provided to be slidably fitted into the key grooves 11f and 11g of the frame 11. The distal end portion 14e of the one key portion 14d has a stepped shape slightly wider in width than the base end side. On the front side of the float key 14, a ring-shaped float guide 27 having an opening 27a is inserted outside the key portions 14d and 14f, and is fixed by screws. On the outer periphery of the float guide 27, a plurality of convex claws 27b are provided.
[0031]
Although the float key 14 is a ring-shaped press-formed member, the key portion 14f is formed by bending the key portion 14d from the outside of the ring-shaped portion, and the key portion 14d is formed by bending the key portion 14d from the inside of the ring-shaped portion. It enables blank board removal.
[0032]
The key portions 14f and 14d of the float key 14 of the present embodiment are smaller in diameter than the fixed frame and the cam frame, and are fitted into and slide-contacted with a key groove (described later) of the zoom frame 16 at the tip of the lens barrel. The key portions 14f and 14d are arranged relatively on the optical axis O side in the radial direction in the lens barrel and parallel to the optical axis. One of the key portions 14f and 14d is formed by bending from the outside of the ring-shaped portion. The position of the bent portion is inside the ring-shaped portion as described above. The connecting part of the part becomes very thin. Therefore, since the key portions 14f and 14d receive some external force from the side surfaces, it is not preferable to bend both the key portions 14f and 14d from outside. Also, the load at the time of the straight guide acts on the key portions 14d and 14f more toward the key portion 14d having the tip portion 14e, but by bending as described above, the strength on the key portion 14d side is increased. Can be increased (because the width of the connection portion with the ring-shaped portion on the key portion 14d side can be increased). If the float key 14 is formed in this manner, the cost of this component can be reduced.
[0033]
The cam frame 15 is an annular member having an opening 15a, and meshes with a long gear 26, a male helicoid screw 15b capable of screwing with the female helicoid screw 11b of the fixed frame 11 on the outer peripheral rear end side, A spur gear shaped gear portion 15c superimposed on the male helicoid screw 15b, a mirror portion 15f for detecting a position near the collapsed rotation end of a cam frame disposed in the male helicoid screw, and And three lock projections 15d which can be slidably inserted into the lock grooves 11c of the fixed frame 11 at a front position separated by a predetermined width.
[0034]
Further, the inner peripheral surface portion 15g of the cam frame 15 has a claw portion 27b of the float guide 27 slidably fitted at a rear end portion thereof, and an inner peripheral guide groove 15h along the circumferential direction, and an optical axis O direction. And three cam grooves 15e skewing. A metal tube 31 serving as an exterior cap portion is fitted and fixed to the outer peripheral portion of the cam frame 15 on the front side of the lock convex portion 15d.
[0035]
The zoom frame 16 is an annular tubular member having a front opening 16a, and three mounting holes on the rear outer peripheral surface 16d of the zoom frame 16 are three slidably fitted into the cam grooves 15e of the cam frame 15. The cam follower 35 is fitted and fixed. A guide groove 16b is formed in the inner peripheral portion of the zoom frame 16 along the direction parallel to the optical axis O, in which the key portion 14d tip 14e and the key portion 14f of the float key 14 are slidably fitted. , 16c.
[0036]
A metal tube 32 serving as an exterior cap portion is fitted and fixed to an outer peripheral portion of the zoom frame 16 in front of a rear outer peripheral portion 16d, and a front decorative plate 33 is attached to a front surface portion. In addition, in the figure, only a part of the front decorative plate 33 is shown.
[0037]
The focus drive frame unit 17 includes a focus drive frame 18, a focus motor 41 that is a stepping motor of a drive source that is fixed to the rear of the focus drive frame 18 by projecting (forming a convex portion), A first-group frame 19, a first-group frame guide rod 42 that supports the first-group frame 19 so as to be able to advance and retreat, and an urging spring that is inserted into the guide rod 42 and is a compression spring that urges the first-group frame 19 backward. 44, a first group frame advance / retreat drive feed screw 41A (FIG. 7) driven to rotate by the focus motor 41, and a PI (photo interrupter) 76 for resetting the advance / retreat position of the first group frame 19 (FIG. 7). Become.
[0038]
The focusing drive frame 18 is a frame member fixed to the inside of the zoom frame 16 with screws. The focusing drive frame 18 has an opening 18a at the center where the first group frame 19 can be inserted, and a focus motor 41 at the upper part. The feed screw 41A and the first group guide rod 42 are supported by the shaft support portion 18b on the side of the focus motor 41 so as to be parallel to the optical axis O. A guide groove 18d for slidingly guiding the first group frame 19 in the direction of the optical axis O is provided in a lower part, and the PI 76 for resetting the advance / retreat position is provided.
[0039]
The focus motor 41 and the shaft support portion 18b are arranged so as to protrude rearward of the focusing drive frame 18. The projecting portion formed by the focus motor 41 and the shaft support portion 18b can enter notches 20g and 37s of the second group frame 20 and the shutter base plate 37, which will be described later, during forward and backward driving.
[0040]
The feed screw 41A is rotatably driven by a focus motor 41 via a pinion at the time of focus driving. The rotation of the feed screw 41A causes the first group frame 19 to move along the first group guide rod 42 while resisting the urging spring 44. It is driven forward and backward. The play of the first group frame 19 in the advancing / retreating direction (the optical axis O direction) is removed by the urging force of the urging spring 44.
[0041]
The first group frame 19 has a first group lens 47 held on the inner peripheral portion thereof. The first group frame 19 has an upper sleeve hole 19b to which the sleeve 43 is adhered and fixed after the lens position adjustment, and a lower lower guide groove portion 18d of the focusing drive frame 18. And a detection shielding plate 19c for the PI 76 are provided. In the first group frame 19, the first group guide rod 42 is slidably fitted in the sleeve 43, and the guide projection 19a of the first group frame 19 is fitted in the guide groove 18d of the focusing drive frame 18. To be able to advance and retreat in the optical axis O direction.
[0042]
The guide rod 42 is adjusted by adjusting the alignment of the first group lens 47, and is fixedly adhered to the focusing drive frame 18.
[0043]
That is, the front end of the guide rod 42 can be fitted into the shaft hole of the zoom frame 16, and the rear end can be fitted into the shaft hole 18 c of the focusing drive frame 18 with a gap corresponding to the position adjustment play. I do. When the focusing drive frame 18 is assembled, the guide rod 42 is inserted through the sleeve 43 of the first lens unit 47, and both ends are supported by the shaft hole of the zoom frame 16 and the shaft hole 18c of the focusing drive frame 18, where the zoom is performed. The optical axis of the first lens group 47 fixed to the first lens group frame 19 is aligned with the inclination of the guide rod 42 in the vertical and horizontal directions with reference to the outer peripheral portion of the frame 16. In the centered state, an adhesive is injected into the gap between the shaft hole 18c and the guide rod 42 to fix the position of the shaft end of the guide rod 42 in the direction orthogonal to the optical axis O. The operation of moving the position of the guide rod 42 can be performed by inserting an operating tool into the recess at the rear end of the guide rod 42. Further, an E-shaped retaining ring (E-ring) 45 is mounted on the guide rod 42 in front of the shaft hole 18c for position regulation in a direction parallel to the optical axis O. A washer 46 is inserted between the hole 18c and the wall surface. The washer 46 prevents the injected adhesive from leaking.
[0044]
The second group frame 20 is provided with a flare stop 20A at an optical stop position C0 (FIG. 11) in front of the opening, and a second group lens 48 is held behind the stop 20A. Three cam followers 36 which are slidably fitted in the cam grooves 15e of the cam frame 15 are fixed to three outer positions of the second group frame 20, and the key portions 14d and 14f of the float key 14 are further fixed to two outer positions. Are provided in the guide holes 20e and 20f. In addition, a cutout portion 20g is provided in an upper portion of the second group frame 20. The notch 20g forms a space that allows the focus motor 41 and the shaft support 18b of the focusing drive frame 18 to enter when the lens barrel 10 is driven for zooming or retracted.
[0045]
The shutter unit 21 includes a shutter base plate 37 provided with a diaphragm opening 37a in the center and a cutout portion 37s above, and a pair (two) of openable and closable light-shielding blades housed on the back side of the shutter base plate 37. Shutter blades 49 and 50, one ND filter 51 having a predetermined dimming rate, and two moving magnet type actuators fixed to a shutter base plate 37, and a shutter actuator serving as a shutter drive source (drive means). 52, a filter actuator 54 serving as a filter drive source, and the shutter blades 49, 50 and a shutter retainer 38 for regulating the direction of the optical axis O of the ND filter 51. The notch 37s of the shutter base plate 37 forms a space that allows the focus motor 41 and the shaft support 18b of the focusing drive frame 18 to enter during zoom driving or collapsing driving.
[0046]
The shutter unit 21 is fixed to and integrated with the rear surface of the second group frame 20. That is, a screw having the screw insertion hole 20d inserted through the screw insertion hole 20d in a state where the locking claws 37b, 37c of the shutter base plate 37 are locked to the engagement portions 20b, 20c of the second group frame 20, is screwed into the screw screw hole 37d of the shutter base plate 37. Then, the shutter base plate 37 is fixed to the rear side of the second group frame 20 and integrated (FIGS. 6 and 7).
[0047]
On the back surface of the shutter retainer 38 of the shutter unit 21, a light shielding sheet 55 made of a flexible sheet material is disposed along a plane perpendicular to the optical axis O (FIGS. 7 and 8). The light-shielding sheet 55 is screwed in the vicinity of the optical axis O, and is supported in close contact with the shutter retainer 38 in an upper half portion in a free state. The light shielding sheet 55 blocks unnecessary light from the cutout portions 20g and 37s of the second group frame 20 and the shutter base plate 37 to the CCD unit side (FIG. 9). When the focus motor 41 and the shaft support 18b enter the notch, the light shielding sheet 55 is pressed by the rear end of the focus motor 41 and elastically deforms rearward, so that the focus motor 41 and the like enter. It becomes possible (FIGS. 8 and 10). The shutter unit 21 will be described later in detail.
[0048]
The inner peripheral surfaces of the internal components such as the fixed frame 11, the cam frame 15, and the zoom frame 16 are coated with anti-reflection coating.
[0049]
Each constituent member of the above-described lens barrel 10 is assembled by the following procedure as an example. Of course, it is also possible to assemble by another procedure. First, the zoom frame 16 is fitted into the inner peripheral portion 15g of the cam frame 15 from the rear side, and the cam follower 35 of the zoom frame 16 is fitted into the cam groove 15e, and the first group frame 19 and the focusing drive unit 17 are mounted. The frame 16 is incorporated into the cam frame 15. Then, the second group frame 20, in which the shutter unit 21 is integrated, is inserted into the cam frame 15, and the cam follower 36 of the second group frame 20 is fitted into the common cam groove 15e.
[0050]
Further, the float key 14 to which the float guide 27 is attached is inserted from the rear side of the cam frame 15, and the key portions 14 d and 14 f are inserted through the guide holes 20 e and 20 f of the second group frame 20. Further, the tip portion 14e of the key portion 14d is fitted into the guide groove 16b of the zoom frame 16, and the key portion 14f is fitted into the guide groove 16c of the zoom frame 16. Thereafter, the convex portion 27b of the float guide 27 is fitted into the inner peripheral guide groove 15h of the cam frame 15. As described above, the convex portion 21b of the float guide 27 fits into the inner peripheral guide groove 15h, and the convex portions 14b and 14c of the float key 14 are guided straight to the fixed frame 11 as described later. The key 14 moves integrally with the cam frame 15 in the direction of the optical axis O in a state where the rotation of the key 14 is restricted with respect to the fixed frame 11.
[0051]
Subsequently, the cam frame 15 in which the zoom frame 16, the second group frame 20, the float key 14, and the like are incorporated is inserted from the rear side of the fixed frame 11, and the male helicoid screw 15b of the cam frame 15 is screwed into the female helicoid screw 11b. And the protrusions 14b and 14c of the float key 14 are fitted into the key grooves 11f and 11g of the fixed frame 11. Therefore, the long gear 26 is inserted into the gear chamber of the fixed frame 11, and the front shaft support hole of the long gear 26 is fitted to the fixed frame side shaft support pin. The CCD holder 22 of the CCD unit 12 in which the CCD 62 and the like are assembled is mounted from the rear, the shaft end of the long gear 26 is fitted into the shaft support hole 22b of the CCD holder 22, and the CCD holder 22 is fixed to the fixed frame 11 with screws. . With the above assembly, the lens barrel 10 is completed.
[0052]
Next, the forward / backward driving operation of the lens barrel 10 will be described.
When the lens barrier 5 is in the closed position as shown in FIG. 1 and the lens barrel 10 is in the collapsed state in which the lens barrel 10 is retracted into the camera, as shown in FIG. The first and second group frames 19, 20 and the like are all held in a housed state. The cam followers 35 and 36 of the zoom frame 16 and the second group frame 20 are respectively located at the retracted end positions of the common cam groove 15e. In this collapsed state, the focus motor 41 is located at a position where it has entered the second group frame 20 and the cutouts 20 g and 37 s of the shutter base plate 37, and the light shielding sheet attached to the shutter holder 38 at the rear end of the focus motor 41. 55 is pressed and held in a state of being deformed rearward. When the notch portions 20g and 37s of the focus motor 41 and the like enter the notch portions 20g and 37s, the second group frame 20 and the like, the focusing drive frame 17 on the zoom frame 16 side, the first group frame 19 and the like are held in an extremely close state.
[0053]
Therefore, when the lens barrier 5 is slid to the open position as shown in FIG. 2, the lens barrel 10 is extended from the retracted state to the photographable wide state shown in FIG. 9 according to an instruction of the control unit in the camera. . That is, the zoom motor 24 is controlled and driven based on the output of the encoder, the long gear 26 rotates, the cam frame 15 is driven to rotate clockwise, and rotates forward through the female and male helicoid screws 11b and 15b. It is paid out. Then, the lock projection 15d of the cam frame 15 is fitted into the lock groove 11c of the fixed frame 11. In the lock groove fitted state, the cam frame 15 rotates between the wide rotation position and the tele rotation position in the photographing enabled state without moving forward and backward by the rotation of the zoom motor 24. On the other hand, the zoom frame 16 is fed out together with the cam frame 15 in a state where the rotation thereof is restricted by the float key 14, and is further moved to a wide position where shooting is possible together with the first group frame 19 via the cam follower 35 by the cam groove 15 e of the cam frame 15. It is paid out. Further, the second group frame 20 is extended with the cam frame 15 in a state where the rotation of the second group frame 20 is restricted by the float key 14, and further extended to a wide position where photographing is possible via the cam follower 36 by the cam groove 15e of the cam frame 15.
[0054]
In the wide state, since the second group frame 20 and the focus motor 41 are at positions separated from each other, the light shielding sheet 55 is held in a state of being in close contact with the shutter retainer 38 by its own elastic force, and the second group frame 20 is cut. Unnecessary light from the notch 20g is blocked.
[0055]
When the zoom motor 41 is driven from the wide state where the image can be taken and the cam frame 15 is further rotated clockwise, the first group frame 19 together with the zoom frame 16 advances and retreats to the tele position in a state where the rotation is restricted by the float key 14. Move (FIG. 10). Similarly, the second group frame 20 is extended to the telephoto position while the rotation of the second group frame 20 is restricted by the float key 14 (FIG. 10). In the telephoto state, the first group frame 19 and the second group frame 20 are located extremely close to each other. Accordingly, the focus motor 41 enters the second group frame 20 and the cutout portions 20g and 37s of the shutter base plate 37, and the light shielding sheet 55 is pressed by the focus motor 41, elastically deformed and inclined rearward. However, the focus motor 41 and the like are located in the cutouts 20g and 37s, and the gap between the focus motor 41 and the second group frame 20 and the shutter base plate 37 is covered with the light shielding sheet 55. Thus, intrusion of unnecessary light from the cutouts 20g and 37s is prevented.
[0056]
The focusing drive operation from the wide state to the telephoto state is performed by a so-called hill-climbing AF method. The focus motor 41 is driven and controlled under pulse control based on contrast data detected from an image signal of the CCD 62. By the rotation of the focus motor 41, the first group frame 19 is driven forward and backward relative to the zoom frame 16 through the feed screw 41A of the focusing drive frame 18 to each focusing position, and a focusing operation is performed.
[0057]
When the lens barrier 5 at the position shown in FIG. 2 is slid in the closing direction after the photographing is completed, the zoom motor 24 is driven to rotate, and the cam frame 15 moves counterclockwise through the wide rotation position to the collapsed rotation position. It is driven to rotate. When the cam followers 35 and 36 slide in the common cam groove 15e and the zoom frame 16, the second group frame 20 and the like are retracted toward the retracted position, but the cam frame 15 is rotated to near the end of the retracted rotation position. Since the rotation position detecting mirror 15f of the cam frame 15 is detected by the cam frame rotation position detection sensor attached to the fixed frame 11, the zoom motor 24 enters the deceleration drive mode according to an instruction from the control unit of the camera. Then, the cam frame 15 reaches the retracted end rotation position and stops.
[0058]
FIG. 11 shows a wide state in which a photographing optical system of the lens barrel can be changed from a collapsed state to a photographable state, and furthermore, an advance / retreat position of each lens group (optical element) with respect to an imaging plane (CCD imaging plane) when the state changes to a telephoto state. FIG. As shown in the figure, the first lens group 47 as the first lens group and the second lens group 48 as the second lens group are substantially moved from the retracted position closer to the image forming surface side to the wide position where photographing is possible. It is extended linearly, and further extended or moved to each telephoto position. The first lens group 47 and the second lens group 48 at the telephoto position are extremely close as shown in FIG. When the first lens unit 47 is driven from the wide position to the telephoto position, the first lens unit 47 is driven so as to slightly retract and then extend again.
[0059]
Here, the electric control system of the camera 1 of the present embodiment will be described with reference to the block diagram of FIG.
The camera 1 has an electric control system for controlling the above-described photographing lens, shutter unit, CCD, image signal processing, and the like. The CPU 101 is control means for controlling the entire camera and individual electric control units. And a zoom motor 24 and a focus motor 41 for driving a first lens group 47 and a second lens group 48, which are photographing lenses, as electric control members controlled by the CPU 101, and a lens drive for the motor. A circuit 107, a shutter actuator 52 as a drive source for rotating the shutter blades 49 and 50, a shutter drive circuit 105 for driving the actuator 52, and a filter as a drive source for rotating the ND filter 51. Actuator 54 and filter drive circuit 10 for driving actuator 54 A CCD 62 serving as an imaging unit, an imaging circuit 102 that processes an imaging signal from the CCD 62, an image processing circuit 103 that performs image processing on an imaging signal output from the imaging circuit 102 to generate an image signal, It has a storage means 104 such as a memory card for storing an image signal, and a display circuit 108 for displaying a captured image or the like based on the image signal.
[0060]
The above-described electric control system controls the camera 1 at the time of shooting. That is, the zoom motor 24 is driven via the CPU 101 to perform zoom driving of the photographing lens. At the time of photographing exposure, a focusing operation is performed based on contrast data captured via the CCD 62. The drive of the shutter actuator 52 and the filter actuator 54 is controlled based on the luminance data, and the shutter blades 49 and 50 and the ND filter 51 are driven to open and close. Further, the image pickup signal taken in via the CCD 62 controlled by the CPU 101 is converted into an image signal by the image pickup circuit 102 and the image processing circuit 103 under the control of the CPU 101 and stored in the storage means 104. Further, an image based on the image signal is displayed on the LCD display unit via the display circuit 108.
[0061]
In the photographing operation, the CPU 101 performs the AE control including the control of the shutter unit 21 as described above, in addition to the zoom and focus control of the photographing lens and the control of the photographing process. For example, as described later, it is determined whether or not to insert the ND filter 51 at a position covering the shutter opening 37a according to the zoom state of the photographing lens and the shutter speed, and control is performed. For example, when the shutter speed is equal to or higher than a predetermined value in a state where the ND filter 51 is in the open position, the position is set so as to cover the ND filter 51 and control is performed so as to switch to a lower shutter speed and perform shooting. I do. Further, the predetermined value is controlled so as to be different depending on the focal length of the photographing lens, and the predetermined value on the short focal length side (wide side) is adjusted by the photographing lens on the long focal length side (tele side). Set to a value shorter than the predetermined value. Further, the CPU 101 also adjusts the sensitivity of the CCD based on the subject brightness data detected by the CCD 62.
[0062]
Next, details of the shutter unit and AE control in the camera 1 of the present embodiment will be described.
As shown in FIG. 11, at the optical stop position C0 in the photographing optical system, the peripheral light flux is distributed substantially around the optical axis O without deviation, and at other positions, for example, the back side of the second group lens 48 At the position, each peripheral light beam and the central light beam are distributed in a biased manner. Therefore, in a conventional photographing optical system, an aperture and a shutter are usually arranged at the aperture position C0.
[0063]
However, in the photographing optical system of the present embodiment, the convex optical portion of the second group lens 48 protrudes forward from the optical stop position C0. Is very close to the concave side on the back side of the first lens unit 47. Therefore, the shutter blades 49, 50 and the ND filter 51 cannot be arranged at the optical stop position C0. Therefore, in the present embodiment, the shutter unit 21 having the shutter blades 49 and 50 and the ND filter 51 is arranged on the back surface of the second lens group 48 as described above.
[0064]
However, as described above, at the rear position of the second lens group, each peripheral light beam and the central light beam are distributed with a bias with respect to the optical axis O. This tendency is remarkable especially in the wide state. Shading may occur due to the deviation of the peripheral light beam. The higher the subject brightness and the earlier the shutter time, the greater the effect of the surrounding light flux blocking state when closing the shutter blades during the entire exposure period, and the more likely shading occurs.
[0065]
Therefore, in the present embodiment, as a countermeasure to prevent the occurrence of the shading, one is to suppress the shading by uniformly shielding the peripheral light flux as much as possible by mechanically controlling the shutter such as the shape of the shutter blade and the rotation operation. In one of the methods, the above-described shading is suppressed by reducing the influence of the bias of the peripheral light beam by exposure control (AE control) using a CCD sensitivity, a shutter speed, and an ND filter.
[0066]
First, the detailed structure of the shutter unit 21 in which the shading prevention measures have been taken and the opening and closing operations thereof will be described with reference to FIGS.
FIG. 13 is an exploded perspective view of components such as a shutter blade and an ND filter incorporated in the shutter base plate of the shutter unit. FIG. 14 is a view showing the attitude of the shutter blades arranged on the shutter base plate in a fully opened state when viewed from the image forming side. FIG. 15 is a diagram illustrating a posture of the shutter blade when the shutter blade starts to be closed as viewed from the image forming side. FIG. 16 is a view showing the attitude of the shutter blade in the middle of closing as viewed from the image forming side. FIG. 17 is a view showing a state in which the shutter blades are in the process of being closed thereafter as viewed from the image forming side, and when peripheral light is shielded. FIG. 18 is a diagram illustrating a posture in a fully closed state when the shutter blade is viewed from the image forming side. FIG. 19 is a diagram showing a change in the peripheral light blocking ratio with respect to the rotation angle of the shutter blade.
[0067]
As described above, the shutter unit 21 includes a shutter base plate 37, two shutter blades 49 and 50 rotatably supported by the base plate 37, and an ND filter 51, and a blade for holding the shutter blade and the ND filter. It includes a holder 38, a light shielding sheet 55 (FIG. 7), a shutter actuator 52 and a filter actuator 54 which are driving sources of a moving magnet type (rotary solenoid).
[0068]
As shown in FIG. 13, the shutter base plate 37 has a shutter opening (exposure opening) 37a at the center, a notch 37s at the upper part, and a second group frame 19 projecting to the front part (subject side). A claw 37b and a screw insertion hole 37e for fastening the second group frame 19 are provided, and an arc-shaped drive pin insertion elongated hole 37i is formed on the lower right side (lower left side in FIGS. 13 and 14), and a lower left side. An arc-shaped drive pin insertion slot 37k is provided on the lower right side in FIGS. Further, on the back surface (imaging plane side) of the shutter base plate 37, blade rotating shafts 37g and 37h protruding at positions separated by a predetermined distance on both sides of the insertion long hole 37i, and separated by a predetermined distance from the insertion long hole 37k. The filter rotation shaft 37j protrudes to the position, the filter closed position stopper 37n and the shutter closed position stopper 37q in the upper portion, the shutter open position stopper 37m in the right position (the left position in FIGS. 13 and 14), and the lower position. A shutter open position stopper 37p is disposed at the bottom.
[0069]
The blade retainer 38 is fixed to the shutter base plate 37 with a predetermined gap provided therebetween, and has an opening corresponding to a central shutter opening, and a surface protection escape for the ND filter 51 at the retracted position. An opening 38a including a portion, a driving pin insertion hole, a screw insertion hole 38b, and the like are provided.
[0070]
The shutter actuator 52 and the filter actuator 54 are fixedly supported at the front part (subject side) of the shutter base plate 37 and at the side position of the second lens group 48. A shutter drive arm 53 having a blade drive pin 53a is fixed to the output shaft of the shutter actuator 52. The blade drive pin 53a is attached to the shutter base plate 37 by being inserted into an arc-shaped long hole 37i. On the other hand, a filter drive arm 55 having a filter drive pin 55a is fixed to the output shaft of the filter actuator 54. The blade drive pin 55a is attached to the shutter base plate 37 by being inserted into an arc-shaped long hole 37k.
[0071]
The shutter blades 49 and 50 have shaft holes 49a and 50a rotatably fitted to the blade rotation shafts 37g and 37h, and drive pin engagement elongated holes 49b and 50b into which the blade drive pins 53a are slidably fitted. Concave bent portions 49c and 50c are formed at the respective central edges that face each other in the assembled state. The shutter blades 49 and 50 assembled to the shutter base plate 37 are rotationally driven in directions opposite to each other from the normal open position (FIG. 14) to the closed position (FIG. 18) at the end of imaging by rotation of the shutter actuator 52. Is done.
[0072]
The ND filter 51 has a predetermined transmittance and reduces a light beam by a predetermined amount. The ND filter 51 has a shaft hole 51a rotatably fitted to the filter rotating shaft 37j, and a drive pin engagement elongated hole 51b into which the filter drive pin 55a is slidably fitted. The ND filter 51 assembled to the shutter base plate 37 rotates between the open position (FIG. 7) retracted from the shutter opening via the drive pin 55a by the rotation of the filter actuator 54 and the opening covering position covering the shutter opening. Driven. When the ND filter 51 is at the above-mentioned opening covering position, the light quantity of the subject incident on the CCD 62 is reduced by a predetermined amount.
[0073]
As shown in FIG. 14, the shutter blades 49 and 50 are supported by the rotating shafts 37g and 37h, and the common blade drive pin 53a is inserted through the drive pin engagement slots 49b and 50b. The main shielding directions of the blades 49 and 50 are the directions of the second quadrant Q2 and the fourth quadrant Q4 of the shutter opening 37a. As described above, due to the arrangement of the shutter, the ambient light tends to be deviated outward with respect to the shutter opening 37a. Therefore, the peripheral light is uniformly blocked, and the following arrangement and blade shape are used to prevent shading. Is adopted.
[0074]
That is, assuming that a vertical bisector of the inter-axis line segment S0 connecting the rotating shafts 37g and 37h is P0, the blade drive pin 53a passes along an arc intersecting the vertical bisector P0. At the initial stage of the rotation of the blade drive pin 53a, the blade drive pin 53a is located on the rotation axis 37h side with respect to the perpendicular bisector P0, and thereafter on the rotation axis 37g side. On the other hand, the perpendicular bisector P0 is positioned so as to be deviated toward the second quadrant Q2 with respect to the optical axis O. The reason for such a bias is that the rotation center of the shutter drive arm 53 is disposed on the rotation shaft 37h side as shown in FIG. 14, the blade drive pin 53a passes along a circular arc locus, and the shutter is moved in the first half of the rotation. Since the drive pin 53a is closer to the rotation shaft 37h than the rotation shaft 37g, the rotation angle of the shutter blade 50 is larger than that of the shutter blade 49 (rotation angular velocity is large). Therefore, when the perpendicular bisector P0 passes on the optical axis O, the timing at which the second quadrant Q2 of the shutter opening 37a is shielded from light is delayed later than that of the fourth quadrant Q4. By shifting the vertical bisector P0 toward the second quadrant Q2, the shielding of the second quadrant Q2 and the fourth quadrant Q4 of the shutter opening 37a is started at the same timing.
[0075]
On the other hand, when the blade drive pin 53a rotates and is positioned on the rotation shaft 37h side, the rotation angular velocity of the shutter blade 49 becomes larger than that of the shutter blade 50. Then, the amount of light blocking on the second quadrant Q2 side of the shutter opening 37a increases earlier than on the fourth quadrant Q4 side.
[0076]
Therefore, the bending angles α1 and α2 of the bent portions 49c and 50c at the center edges of the shutter blades 49 and 50 are set to α1> α2 so that the difference in the shielding light amount due to the shutter blade rotation speed difference does not occur. I have. Thus, even during the closing operation, the shutter timing of the shutter opening 37a by the bent portion 49c of the shutter blade 49 is delayed, and the shielding timing of the shutter opening 37a by the bent portion 50c of the shutter blade 50 is advanced.
[0077]
By adopting the shapes of the shutter blades 49 and 50 and the arrangement of the rotating shafts 37g and 37h as described above, the peripheral light in the second and fourth quadrants distributed to the outside is uniformly distributed as described later. Can be shielded.
[0078]
The process of rotating the shutter blades 49 and 50 by the shutter actuator 52 to change the shutter opening 37a from the fully opened state to the fully closed state is shown in FIG. 14 to FIG. That is, the rotation operation is started from the fully opened state in FIG. 14, and first, the shutter opening 37a is started to be closed as shown in FIG. 15, and during the closing operation in FIG. 16, the peripheral light flux S2 on the second quadrant Q2 is It is shielded in the same state as the peripheral light beam S4 on the four quadrant Q4. Further, in the vicinity of the end of the light shielding operation in the closing operation in FIG. 17, the peripheral light beams S2 and S4 are simultaneously shielded. Then, the rotation operation ends as shown in FIG.
[0079]
FIG. 19 shows the change in the light blocking ratio (%) of the peripheral light with respect to the rotation angle (°) of the shutter actuator drive arm 53 for the peripheral light flux S2 in the second quadrant Q2 and the peripheral light flux S4 in the fourth quadrant Q4. FIG. 4 is a diagram showing that the peripheral light flux S2 and the peripheral light flux S4 are shielded in substantially the same change state.
[0080]
As described above, in the shutter closing operation of the shutter unit 21, the peripheral light beam S2 in the second quadrant Q2 and the peripheral light beam S4 in the fourth quadrant Q4 are shielded in a substantially uniform state, so that the shutter opening 37a The difference in the amount of peripheral light due to the quadrant is hardly generated, and the occurrence of shading is suppressed.
[0081]
Next, AE control in the camera 1 of the present embodiment in which measures for preventing shading are taken will be described with reference to FIGS.
20 and 21 are AE program diagrams in the other cameras of the present embodiment. FIG. 20 is an AE program diagram in a zoom wide state, and FIG. 21 is an AE program diagram in a zoom telephoto state. .
[0082]
In the camera 1 according to the present embodiment, as described above, the shutter blades 49 and 50 are disposed at the rear position of the second lens group 48 different from the optical stop position C0 of the photographing optical system. Therefore, as shown in FIG. 11, at the positions where the shutter blades 49 and 50 are arranged, the center light beam and the peripheral light beam are shifted in both the wide state and the telephoto state. That is, the peripheral light beam passes through a position farther from the optical axis than the center light beam. This is particularly noticeable in the wide state. On the other hand, during the closing operation of the shutter blades 49, 50, the shutter is blocked from outside the shutter opening 37a. Therefore, the peripheral light beam is shielded first. As a result, the amount of light imaged at the central portion and the peripheral portion differs, and so-called shading occurs. The manifestation of such a phenomenon depends on the shutter speed and the focal length of the photographing optical system.
[0083]
As for the shutter speed (shutter speed), the higher the speed, the larger the exposure amount during the closing operation of the shutter blades is compared with the total exposure amount. Therefore, the higher the shutter speed is, the more the above-mentioned shading becomes a problem.
[0084]
On the other hand, the focal length of the photographing optical system is different from the optical stop position C0 of the photographing optical system at the position different from the optical stop position C0, as is clear from the comparison between the wide and telephoto states in FIG. The shift amount is larger on the wide side than on the tele side. This means that, on the wide side, the rotation range in which the shutter blade blocks only the peripheral light beam is widened. Therefore, the shading as described above becomes more problematic on the wide side.
[0085]
In the camera 1 of the present embodiment, in order to effectively prevent the above-described shading based on the above-described characteristics, AE control to which the AE program diagram of FIGS. . In the camera 1 of the present embodiment, the shutter blades only perform the closing operation from the fully open state at the time of shooting. That is, the imaging operation by the CCD 62 is started in the fully opened state of the shutter blade, and the imaging operation is ended by closing the shutter blade when a predetermined time has elapsed.
[0086]
FIGS. 20 and 21 are examples of AE program diagrams in the wide state and the telescopic state according to the present embodiment. More specifically, in the camera 1 according to the present embodiment, when the flash emission is off, the automatic control under the control of the CPU 101 is performed. FIG. 7 is an AE program diagram when a sensitivity mode and a program mode are set. Note that in the following description, the Bv value is a bright value indicating the detected subject luminance. The Sv value is a sensitive value indicating the CCD sensitivity, is set via the CPU 101, and corresponds to the ISO sensitivity. The Ev value is an exposure value indicating the amount of exposure. The Tv value is a time value and corresponds to a shutter speed set by the CPU 101. The Av value is an aperture value indicating the aperture, is set by the insertion state of the ND filter 51 controlled by the CPU 101, and corresponds to the F value.
[0087]
The upper left diagrams of FIGS. 20 and 21 are diagrams showing the automatic sensitivity setting when the lens barrel is set to the wide side or the tele side, and shows the CCD sensitivity versus Bv value of the subject brightness. The Sv values are shown. On the wide side, at a Bv value of 3.5 or more, and on the tele side, at a Bv value of 6.8 or more, the Sv value is lowered by one step by lowering the sensitivity of the CCD 62 as an image sensor. The switching of the sensitivity of the CCD 62 prevents the shutter speed from increasing when the subject brightness is high.
[0088]
On the other hand, the lower right diagrams of FIGS. 20 and 21 show the Av value of the aperture with respect to the Tv value of the shutter speed set when the lens barrel is set to the wide side or the tele side. First, on the wide side shown in the lower right of FIG. 20, the Av value is changed so that the shutter speed does not become faster than 1/500 second (Tv value is 9).
In other words, when the Bv value of the subject luminance is close to 7.5, the aperture is 3.3 and the shutter speed is 1/500 second. In this case, the ND filter 51 is inserted into the shutter opening 37a. The shutter speed is switched to 1/60 sec by switching the Av value to 6.3 without changing the aperture diameter. As described above, even in the high luminance state on the wide side, the shutter speed on the lower side is applied.
[0089]
On the tele side shown at the lower right of FIG. 21, the Av value is changed so that the shutter speed does not become faster than 1/1000 second (Tv value is 10). In other words, when the Bv value of the subject brightness becomes close to 10, the aperture becomes 4.9 and the shutter speed becomes 1/1000 sec. However, the ND filter 51 is inserted into the shutter opening 37a to reduce the light, By switching the value to 7.9, the shutter speed is reduced to 1/125 second. As described above, even in the high luminance state on the tele side, the shutter speed on the lower side is applied.
[0090]
As described above, in the camera 1 of the present embodiment, whether to insert an ND filter on the wide side and the tele side is determined based on whether or not the shutter speed is equal to or higher than a predetermined value. Then, the predetermined value on the wide side (short focus side) where shading is likely to occur is set to a lower speed side than the tele side. In other words, the shooting at high speed in wide mode is limited so as to be slower than the shooting in telephoto. As a result, the occurrence of shading under each shooting condition is suppressed, and an appropriate shooting result is always obtained.
[0091]
Further, according to the camera 1 of the present embodiment, it is possible to arrange the shutter unit 21 at a position different from the position of the optical diaphragm regardless of the position of the optical diaphragm, thereby increasing the degree of freedom of the optical system design, and The size can be reduced. The position of the optical diaphragm is a position on the convex surface of the second group lens 48 in the photographing optical system of the present embodiment, and the concave surface of the first group lens 47 is located very close to the front of the position. Therefore, the shutter unit 21 is not arranged at the position of the optical stop, but is arranged at the back of the second lens group 48. As a result, the first lens group and the second lens group can be brought close to each other, so that the first lens group can be made compact at the time of collapsing and the focusing optical system can be made longer (generally, in the case of two-group zoom, the first lens group and the The distance between the group lenses is reduced).
[0092]
Further, in the camera 1 of the present embodiment, even when the shutter unit 21 is arranged at a position other than the position of the optical aperture as described above, the shape of the shielding portions of the shutter blades 49 and 50 that suppress the occurrence of shading in the peripheral portion is set. Has adopted. That is, concave bent portions 49c and 50c having different shapes are provided at the central edges of the shutter blades 49 and 50 so as to evenly shield the peripheral light beam.
[0093]
The shutter unit 21 is supported integrally with the second group frame 20 that holds the second group lens 48. In the supported state, the shutter units 21 are mounted on the shutter unit 21 and actuated by the actuators 52 and 54 that are the drive sources of the shutter and the filter. By arranging between the optical diaphragm position and the shutter blade on the second group lens 48 side, the length of the photographing optical system along the optical axis O direction can be shortened.
[0094]
【The invention's effect】
As described above, the arrangement of the light-shielding blades of the present invention is made appropriate, and furthermore, the occurrence of a light-shielding light amount difference between the light-shielding blades is reduced, so that more appropriate exposure can be performed and the size of the device can be reduced. Alternatively, a camera can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an appearance of a camera in which a lens barrel according to an embodiment of the present invention is incorporated, in a barrier closed state.
FIG. 2 is a perspective view showing an appearance of the camera of FIG. 1 in a barrier open state.
FIG. 3 is a view showing an appearance of a lens barrel incorporated in the camera in an extended state.
FIG. 4 is an exploded perspective view of the components on the fixed frame side of the lens barrel in FIG. 3 as viewed from the subject side.
FIG. 5 is an exploded perspective view of components of the lens barrel shown in FIG. 3 on the cam frame side as viewed from the subject side.
6 is an enlarged exploded perspective view of the second group frame and the shutter unit in the lens barrel of FIG. 3 as viewed from the subject side.
7 is an exploded perspective view of the focusing drive unit and the integrated second group frame and shutter unit in the lens barrel of FIG. 3 as viewed from the image forming side.
8 is a view showing an upper half portion of a longitudinal section of the lens barrel of FIG. 3 in a collapsed state.
9 is a view showing an upper half part of a longitudinal section of the lens barrel of FIG. 3 in a wide state.
FIG. 10 is a view showing an upper half part of a longitudinal section of the lens barrel of FIG. 3 in a telephoto state.
FIG. 11 is a view showing a wide state in which an image can be photographed from a retracted state in the photographing optical system of the lens barrel shown in FIG. 3 and a retracting position of each lens group with respect to an image forming plane when the state changes to a telephoto state.
FIG. 12 is a block diagram of an electric control system in the camera of FIG. 1;
FIG. 13 is an exploded perspective view of components such as a shutter blade and an ND filter incorporated in a shutter base plate of a shutter unit in the lens barrel of FIG. 3;
FIG. 14 is a view showing a posture of the lens barrel shown in FIG. 3 in a fully opened state when a shutter blade disposed on a shutter base plate is viewed from an image forming side.
FIG. 15 is a diagram showing a posture of the lens barrel in FIG. 3 in a state where the shutter blades start to be closed as viewed from the image forming side.
FIG. 16 is a view showing a posture of the lens barrel of FIG. 3 in a state in which shutter blades are being closed when viewed from the image forming side.
FIG. 17 is a view showing a state in which the shutter blades in the lens barrel in FIG. 3 are in the process of being closed after the shutter blades are viewed from the image forming side and when peripheral light is blocked.
18 is a view showing a posture of the lens barrel in FIG. 3 in a fully closed state when a shutter blade is viewed from an image forming side.
FIG. 19 is a diagram showing a change in a peripheral light blocking ratio with respect to a rotation angle of a shutter blade in the lens barrel of FIG. 3;
FIG. 20 is an AE program diagram in the zoom wide state in the camera of FIG. 1;
FIG. 21 is an AE program diagram in the zoom telephoto state in the camera of FIG. 1;
[Explanation of symbols]
21… Shutter unit
(Light control device, shutter device)
47 ... 1 group lens (first lens group)
48 Two-group lens (second lens group)
49, 50: shutter blades (light-shielding blades)
51 ND filter (filter)
52… Shutter actuator
(Drive source, drive means)
101 CPU (control means)
C0: Optical stop position
Tv: value indicating shutter speed

Claims (8)

In a light amount adjusting device arranged in an optical path of an optical system,
A pair of light-shielding blades disposed on the opposite side with respect to an optical stop position of the optical system with an optical element constituting a part of the optical system therebetween,
And a driving means for driving the opening and closing of the opening by rotating the pair of light shielding blades in directions opposite to each other. The light amount adjusting device according to claim 1, wherein each of the light-shielding blades substantially uniformly shields a peripheral light beam of the optical system when the light-shielding blade is opened and closed. A lens having an optical surface protruding from the optical stop position,
A light-shielding vane arranged on the opposite side to the optical surface of the lens to open and close an opening;
A drive source for driving the light-shielding blades, wherein the drive source is disposed on a side of the lens. The light amount adjusting device according to claim 3, wherein the drive source is disposed in a space between the optical stop position and the light shielding blade in the optical axis direction. With respect to the optical stop position of the optical system, it is arranged on the opposite side with respect to the optical element constituting a part of the optical system, and can be moved to a position where the exposure opening of the optical system is opened and a position where it is shielded. A shutter device having light-shielding blades,
A filter disposed in an optical path of the optical system, the filter having a predetermined transmittance, and being movable between a position where the exposure opening is opened and a position where the exposure opening is covered;
Control means for determining whether or not to move the filter to the position to cover the filter in accordance with a zoom state of the optical system and a shutter speed. When the speed is higher than a predetermined value, the camera takes a picture at a lower shutter speed as a position covering the filter. A first lens group having a concave exit surface; and a second lens group having a convex surface on which light emitted from the first lens group is incident. A zoomable optical system in which an optical stop position is located between the optical system and the second lens group;
A shutter device disposed behind the second lens group and having a light-shielding blade movable between a position where the exposure opening is opened and a position where the exposure opening is blocked;
A filter device disposed behind the second lens group, the filter device having a filter having a predetermined transmittance, the filter device being movable to a position to open and cover the exposure opening,
Control means for determining whether or not to move the filter to the position to cover the filter in accordance with a zoom state of the optical system and a shutter speed. When the speed is higher than or equal to a predetermined value, the camera moves to a position where the filter is covered and shoots using a lower shutter speed. In the state where the filter is in the open position, when the shutter speed at the time of photographing is equal to or higher than a predetermined value, the control unit controls the movement of the filter to the position covering the filter. 7. The camera according to claim 5, wherein the camera is controlled to adopt a different value depending on a focal length of the optical system. 8. The method according to claim 7, wherein the predetermined value of the shutter speed when the optical system is on the short focal length side is higher than the predetermined value of the shutter speed when the optical system is on the long focal length side. The described camera.

Images