JP2002072284A - Light quantity adjusting device, lens device, and image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that the peripheral light quantity is made uneven because the center of a light passing port is moved when light-shielding blades constituted of two blades are driven. SOLUTION: In the light quantity adjusting device which possesses two light- shielding blades 131c and 131d by which the aperture area of the light passing port S is changed by mutually moving in directions opposite to each other within a surface orthogonal with an optical axis relative to a device main body; and a driving lever 131b turned by being connected with the light-shielding blades and driving two light-shielding blades, the light-shielding blades are moved and guided by meshing guide shafts 131e1 and 131e2 provided at either the device main body or the light-shielding blades with guide groove 131c2 and 131d2 formed at the other. At least one guide groove out of the guide grooves to respectively move and guide two light-shielding blades is formed into a curved shape within the surface orthogonal with the optical axis.

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 used for an image pickup device such as a video camera or a lens device.

[0002]

2. Description of the Related Art As a zoom lens for a video camera, for example, there is a zoom lens composed of four lens groups of a fixed convex, a movable concave, a fixed convex, and a movable convex in order from the subject side.

FIGS. 12A and 12B show a lens barrel structure of a general zoom lens having a four-group lens structure. (B) shows a cross section taken along line AA in (A).

The four lens groups 201a to 201d constituting the zoom lens are composed of a fixed front lens 201.
a, a variator lens group 201b that performs a zooming operation by moving along the optical axis, a fixed afocal lens 201c, and a focal plane maintenance and focusing during zooming by moving along the optical axis. And a focusing lens group 201d.

The guide bars 203, 204a, and 204b are arranged in parallel with the optical axis 205, and guide and stop the moving lens group. The DC motor 206 is a driving source for moving the variator lens group 201b.

The front lens 201a is held by the front lens barrel 202, and the variator lens group 201b is
It is held at 1. Also, the afocal lens 201
c denotes an intermediate frame 215 and a focusing lens group 201d.
Are held by the RR moving ring 214.

The front lens barrel 202 is positioned and fixed to a rear lens barrel 216. A guide bar 203 is positioned and supported by the two lens barrels 202 and 216, and a guide screw shaft 208 is rotatably supported. I have.
The guide screw shaft 208 is driven to rotate by the rotation of the output shaft 206 a of the DC motor 206 being transmitted through a gear train 207.

A V-moving ring 211 for holding the variator lens group 201b includes a pressing spring 209 and the pressing spring 20.
And a ball 210 which engages with a screw groove 208a formed in the guide screw shaft 208 by a force of 9 by the DC motor 206.
By being driven to rotate, 8 moves forward and backward in the optical axis direction while being guided and regulated by the guide bar 203.

Guide bars 204a, 204 are provided on the rear barrel 216 and the intermediate frame 215 positioned in the rear barrel 216.
04b is fitted and supported. The RR moving ring 214 can advance and retreat in the optical axis direction while being guided and rotated by the guide bars 204a and 204b.

Guide bars 204a and 204 are provided on an RR moving ring 214 for holding the focusing lens group 201d.
b is formed with a sleeve portion that is slidably fitted to the RR moving ring 2 in the optical axis direction.
14 and are integrated with each other.

The stepping motor 212 rotationally drives a lead screw 212a formed integrally with its output shaft. The RR moving ring 21 is attached to the lead screw 212a.
The RR moving ring 214 moves in the optical axis direction while being guided by the guide bars 204a and 204b by the rotation of the lead screw 212a with the engagement of the rack 213 assembled to the rack 4.

As a drive source for the variator lens group, a stepping motor may be used in the same manner as the drive source for the focusing lens group.

The front lens barrel 202, the intermediate frame 215, and the rear lens barrel 216 form a lens barrel body that substantially accommodates a lens or the like.

When the lens group holding frame is moved by using such a stepping motor, after detecting that the holding frame is located at one reference position in the optical axis direction using a photo interrupter or the like, The absolute position of the holding frame is detected by continuously counting the number of drive pulses applied to the stepping motor.

FIG. 13 shows an electrical configuration of a camera body in a conventional imaging apparatus. In this figure, the same reference numerals as in FIG. 11 denote the components of the lens barrel described in FIG.

Reference numeral 221 denotes a solid-state imaging device such as a CCD;
Denotes a drive mechanism of the variator lens group 201b, and includes a motor 206 (or a stepping motor), a gear train 207.
And a guide screw shaft 208 and the like.

Reference numeral 223 denotes a focusing lens group 201d.
And includes a stepping motor 212, a lead screw shaft 212a, a rack 213, and the like.

Reference numeral 224 denotes a drive mechanism of the diaphragm device 235 disposed between the variator lens group 201b and the afocal lens 201c.

Reference numeral 225 denotes a zoom encoder, and 227 denotes a focus encoder. Each of these encoders detects the absolute position of the variator lens group 201b and the focusing lens group 201d in the optical axis direction. When a DC motor is used as the variator driving source as shown in FIG. 11, an absolute position encoder such as a volume is used, or a magnetic type is used.

When a stepping motor is used as a drive source, a method of continuously counting the number of operation pulses input to the stepping motor after arranging the holding frame at the reference position as described above is used. General.

Reference numeral 226 denotes an aperture encoder, which employs a system in which a Hall element is disposed inside an aperture drive source 224 such as a motor and detects the rotational positional relationship between a rotor and a stator.

A CPU 232 controls the camera. A camera signal processing circuit 228 performs predetermined amplification, gamma correction, and the like on the output of the solid-state imaging device 221. The contrast signal of the video signal that has undergone these predetermined processes passes through the AE gate 229 and the AF gate 230. That is, the optimum signal extraction range for exposure determination and focusing is set by this gate in the entire screen. The size of this gate is variable,
There may be a case where a plurality is provided.

Reference numeral 231 denotes an AF signal processing circuit which processes an AF signal for AF (auto focus), and generates one or a plurality of outputs related to a high frequency component of a video signal. 233 is a zoom switch, and 234 is a zoom tracking memory. Zoom tracking memory 234
Stores information on the focusing lens position to be set in accordance with the subject distance and the variator lens position during zooming. Note that C is used as the zoom tracking memory.
The memory in the PU 232 may be used.

For example, the photographer sets the zoom switch 23
3 is operated, the CPU 232 determines the current variator as a detection result of the zoom encoder 225 so that the predetermined positional relationship between the variator lens and the focusing lens calculated based on the information of the zoom tracking memory 234 is maintained. The absolute position in the optical axis direction of the lens and the calculated position of the variator lens to be set, and the current absolute position of the focus lens in the optical axis direction as a detection result of the focus encoder 227 and the calculated focus lens should be set. The drive of the zoom drive mechanism 222 and the focussing drive mechanism 223 is controlled so that the positions match each other.

In the auto focus operation, the CPU 2 sets the output of the AF signal processing circuit 231 to a peak so that
Reference numeral 32 controls the driving of the focusing drive mechanism 223.

Further, in order to obtain an appropriate exposure, the CPU 2
Reference numeral 32 designates the average value of the output of the Y signal passing through the AE gate 229 as a predetermined value, and controls the drive of the aperture driving mechanism 224 so that the output of the aperture encoder 226 becomes the predetermined value, thereby controlling the aperture diameter.

Here, as a diaphragm device mounted on a conventional video camera, there is, for example, one having a configuration shown in FIG. This aperture device is a two-blade type,
The diaphragm blades 23a and 23b are connected to a seesaw drive lever 23 by one rotating electromagnetic actuator (motor) 23c.
It is configured to be driven via d. In addition, 23e is a main plate (namely, a casing) of the expansion device.

In this diaphragm device, an electromagnetic drive having a rotor made of a cylindrical permanent magnet (or a rotor magnetized on the outer peripheral surface of a cylindrical metal body) is used as a drive source of the diaphragm blade. An actuator is used, and the actuator controls a rotation position and a rotation amount (rotation angle) by detecting a change in movement of a magnetic pole on an outer peripheral surface of the rotor by a Hall element.

In addition, there is an aperture device having a configuration shown in FIGS. FIG. 15 shows an open state of the aperture device, and FIG. 16 shows a fully closed state of the aperture device. FIG.
Indicates an arrangement relationship of each component in the diaphragm device in the optical axis direction.

Reference numeral 13a denotes an actuator for opening and closing the aperture blade 13d. An intermediate portion in the longitudinal direction of the drive lever 13c 'is press-fitted and held on the output shaft 13a1 of the actuator 13a. The drive lever 13
Pin portions 13c1 'and 13c' are formed at both ends of c '. The pin portion 13c1 'is engaged with the long hole portion 13d1 of the first aperture blade 13d.

Further, a guide groove 13d2 is formed on the first diaphragm blade 13d, and a guide pin 13f1 formed on a base member 13f of the diaphragm device is engaged with the guide groove 13d2. I have.

Similarly, the pin portion 13c2 'is engaged with the long hole portion 13e1 of the second diaphragm blade 13e. Also, the second
A guide groove 13e2 is formed on the aperture blade 13e, and the guide member 13e2 has a base member 13e.
The guide pin 13f2 formed in f is engaged.

In the aperture device constructed as described above,
When the actuator 13a rotates, the drive lever 13c also rotates, so that both the diaphragm blades 13d and 13e are driven in the vertical direction in the figure. At this time, the aperture blade is vertically moved and guided by the engagement between the guide groove and the guide pin.

By the way, in recent years, the photographing lens has been required to be reduced in size and diameter. However, in the conventional diaphragm device, in order to drive one diaphragm blade, at least two guide pins are erected on the base plate side of the diaphragm device, and a linearly extending guide for engaging the guide pin is formed on the blade side. At least two rails are required.

For this reason, the size of the aperture device necessarily increases in the driving direction of the aperture blade. And as a result,
The outermost diameter of the taking lens on which the aperture device is mounted becomes large.

To reduce the size of the apparatus, a type using one guide pin (a so-called blade swing type two-blade aperture device) has also been proposed.

[0037]

However, even in the conventional blade swinging type two-blade aperture device, since the guide groove formed in the aperture blade extends linearly, the aperture blade is in an open state and is not fully open. In the process of moving between the closed state and the closed state, there is a problem that the amount of movement of the center of the light passage opening formed by these diaphragm blades (the center of gravity of the opening area) becomes large.

FIG. 18 is a diagram for explaining this problem. In this figure, the aperture blades 13d, 13d
When e is driven from the open state to the fully closed state, the centers of the light passage ports move in the order of 131g1 to 131g4.

When the center of the light passage opening is largely displaced with respect to the optical axis position, a uniform peripheral light amount cannot be obtained, and the optical performance deteriorates.

[0040]

In order to solve the above-mentioned problems, in the present invention, the apparatus body is moved in opposite directions in a plane orthogonal to the optical axis to change the opening area of the light passage. A plurality of light-shielding blades, and a drive lever connected to the light-shielding blades and rotating to drive the two light-shielding blades, and a guide shaft provided on one of the apparatus body and the light-shielding blade is formed on the other. In the light amount adjusting device that moves and guides the light-shielding blade by engaging with the set guide groove, at least one of the guide grooves for moving and guiding the two light-shielding blades is formed in a plane orthogonal to the optical axis. It is formed in a curved shape.

Thus, the degree of freedom in controlling the attitude and position of the driven light shielding blade can be increased as compared with the case where the guide groove is formed in a linear shape. By setting the curved shape of the guide groove so that the center of the light passage opening (the center of gravity of the opening area) is maintained at a substantially constant position in the plane orthogonal to the optical axis when the light shielding blade is driven, Movement of the center position of the light passage opening during driving can be substantially eliminated, and by making the center position substantially coincident with the lens optical axis or the photographing optical axis, it becomes possible to obtain a uniform peripheral light amount.

Specifically, when the light shielding member is driven, the curved shape of the guide groove is defined by a distance from a straight line passing through the center of the light passage opening in a plane orthogonal to the optical axis to a connecting portion between the light shielding member and the driving lever. The sum of the distance from the straight line to the position where the guide groove is engaged with the guide shaft in the guide groove is set so as to maintain a substantially constant value. This makes it possible to move the light shielding blades in opposite directions to each other in the plane orthogonal to the optical axis without swinging about the connection portion and the guide shaft, and to provide a light passage opening when the light shielding blades are driven. Can be almost eliminated.

According to the present invention, in the connecting portion between the light-shielding blade and the drive lever, a connection shaft provided on one of the light-shielding blade and the drive lever is rotatably fitted in a hole formed on the other. It is suitable for a light amount adjusting device of a type in which one light shielding blade can move and guide the light shielding blade by a pair of guide shafts and guide grooves, thereby realizing a small light amount adjusting device with good optical performance. It becomes possible.

[0044]

FIG. 1 and FIG. 2 show a lens barrel (lens device) provided with an aperture unit (light amount adjusting device) according to an embodiment of the present invention. This lens device is used for a video camera (imaging device) (not shown).

In these figures, reference numeral 1 denotes a first lens which is a front lens.
A group lens, 2 is a variator group lens, 3 is a fixed afocal group lens, and 4 is a focusing group lens.

Reference numeral 5 denotes a front lens barrel for holding the first group lens 1. As shown in FIG. 3, the front lens barrel 5 has openings on the upper surface and the image forming surface side, and has left and right side surfaces and lower surfaces having wall surfaces extended in the image forming surface direction. ing.

A light-shielding line 5a having a matte surface is formed on the inner wall of the lower surface of the front lens barrel 5. The light-shielding line 5a prevents reflection of light on the inner wall of the lower surface, and generates harmful reflection ghosts. Here, the light-shielding line 5a is formed by upward sliding in FIG. 3 in molding the mold. For this reason, the inner wall shape of the front lens barrel 5 has a shape that can be formed by sliding upward in all the parts requiring dimensional accuracy. In other words, among the inner wall shapes of the front lens barrel 5, the lower holes 5b and the like of the fixing screws, which do not require much accuracy, are formed by a molding method such as a slide in a slide. The reference holes 5h and 5g of the guide shafts 6a and 6b cannot be formed.

If the slide-in-slide molding method described above is used, there is a problem that molding variation is so large that desired optical performance cannot be guaranteed.

For this reason, in the present embodiment, as shown in FIG.
Reference grooves 5g and 5h are formed by forming reference grooves regulated in three directions by 5d, and accurately fitted to four outer diameters of the guide shafts 6a and 6b by reference ribs 5e and 5f regulated in the horizontal direction by sliding upward. Can be formed.

Reference numeral 7 denotes a rear lens barrel which is joined to the rear part of the front lens barrel 5. The rear barrel 7 includes a low-pass filter holder 7b and a CCD holder 7c for holding a CCD (not shown).
And As shown in FIG. 5, the rear barrel 7 has an opening surface facing the left and right direction and the direction of the optical axis subject, and is used as a reference for contact with the front lens barrel 5 extended in the direction of the optical axis subject. It has one side surface that supports the surface 7a.

Since the rear barrel 7 in this embodiment does not have a light shielding means on the inner wall thereof, the configuration of the slide of the mold is, as shown in FIG. The guide shaft 6
The reference holes 7d and 7e for positioning and holding a and 6b can be easily and accurately formed by sliding in the forward direction, and their shapes are formed as perfect circles as shown in FIG.

In this embodiment, since the light blocking means is not provided on the inner wall of the rear lens barrel 7, the reference hole is formed by sliding forward. However, when the light blocking means is provided, the above-described front lens barrel is used. As in the case of No. 5, it can be formed with high precision by sliding in the left-right direction.

The guide shafts 6a and 6b are positioned and held by fitting into the reference holes 5g and 5h of the front lens barrel 5 and the reference holes 7d and 7e of the rear lens barrel 7 formed as described above.

The V-moving ring 8 holding the variator group lens 2 has a sleeve 8a fitted on the guide shaft 6a on the reference positioning side and a U-groove 8b fitted on the guide shaft 6b on the steadying side. Thus, the position of the variator group lens 2 on the optical axis is determined, and the rotation of the V moving ring 8 around the guide shaft 6a in a plane orthogonal to the optical axis is prevented. The inclination (falling) of the variator group lens 2 with respect to the optical axis direction is ensured by increasing the fitting length of the sleeve 8a to the guide shaft 6a.

A rack (not shown) is attached to the V-moving ring 8 so as to be rotatable in the optical axis direction without play in the optical axis direction. This rack, as shown in FIG.
It engages with the screw shaft 10a of the motor 10. When the PZ motor 10 rotates and the screw shaft 10a rotates, the V-moving ring 8 is driven forward and backward in the optical axis direction by the engagement between the screw shaft 10a and the rack.

RR holding focusing group lens 4
The movable ring 9 has a sleeve 9a fitted on the guide shaft 6b on the reference positioning side, and has a U groove 9b fitted on the guide shaft 6a on the steadying side. Thus, the optical axis position of the focusing group lens 4 is determined, and the rotation of the RR moving ring 9 around the guide shaft 6b in a plane orthogonal to the optical axis is prevented. The inclination (falling) of the focusing lens unit 4 with respect to the optical axis direction is determined by the guide shaft 6 of the sleeve 9a.
This is ensured by increasing the fitting length for b. Further, the reason why the guide shafts on the reference positioning side of the V moving ring 8 and the RR moving ring 9 are different is to secure the respective moving ranges when the fitting length of each sleeve is increased. is there.

A rack (not shown) is attached to the RR moving ring 9 so as to be rotatable in the optical axis direction and without play in the optical axis direction. This rack is, as shown in FIG.
It meshes with the screw shaft 11a of the F motor 11. AF
When the motor 11 rotates and the screw shaft 11a rotates, the RR moving ring 9 is driven forward and backward in the optical axis direction by the engaging action between the screw shaft 11a and the rack.

The intermediate frame 12 for holding the fixed afocal group lens 3 has a reference positioning hole 12 as shown in FIG.
a and the anti-sway slot 12b are formed, and the optical axes of the afocal group lens 3 are positioned by fitting the guide shafts 6a and 6b, respectively. However, the V-moving ring 8 and the RR-moving ring 9 guarantee the fall of the lens held by each by setting the sleeve length on the reference positioning side to be long, whereas the sleeve length of the intermediate frame 12 is 2
Since the length of the sleeve of one moving group lens is long, it is difficult to set it long. For this reason, three engagement portions with the front lens barrel 5 are formed in the intermediate frame 12 to ensure that the afocal group lens 3 falls down. Note that 12c, 12d, 1
Reference numeral 2e denotes a locking portion formed on the intermediate frame 12. The locking portions 12c, 12d, and 12e are respectively engaged with locking grooves 5i and 5j and a long hole-shaped locking groove 5k formed in the front lens barrel 5 corresponding thereto.

First, one of the locking portions 12c and 12d is fitted into one of the locking grooves 5i and 5j of the front lens barrel 5 to define the position of the intermediate frame 12 in the optical axis direction. The engagement of the opposite (other) engaging portion with the other engaging groove prevents the intermediate frame 12 from falling in the X-axis direction in FIG. The engagement of the locking portion 12e with the locking long hole 5k prevents the intermediate frame 12 from falling in the Y-axis direction in FIG. In addition, each of the locking portions may be set to be fitted to the locking groove, or may be set to be lightly press-fitted.

The assembly of the lens barrel constructed as described above is performed in the following procedure. First, two guide shafts 6
With the V moving ring 8, the intermediate frame 12, and the RR moving ring 9 penetratingly held by the a and 6b, the intermediate frame 12 is inserted into the front lens barrel 5 from the direction orthogonal to the optical axis, and the engagement grooves 5i and 5j are formed. , 5k are engaged with the locking portions 12c, 12d, 12e of the intermediate frame 12.

Thereafter, the guide shafts 6a and 6b are
The rear lens barrel 7 is assembled by sliding in the reference holes 5g and 5h from the optical axis direction by the fitting length of these guide shafts, and the rear lens barrel 7 is assembled from the optical axis direction and fixed to the front lens barrel 5. As a result, the outer periphery of the lens barrel is substantially sealed.

After that, the PZ motor 10, the AF motor 11, and the aperture unit 13 are assembled in a direction perpendicular to the optical axis to complete a lens barrel unit.

As another assembling method, the guide shafts 6a and 6b are incorporated in the rear barrel 7 from the optical axis direction, and the RR moving ring 8, the intermediate frame 12 and the V moving ring 9 are sequentially arranged. In the direction of the optical axis. Then, the front frame 5 is dropped from the direction perpendicular to the optical axis until the intermediate frame 12 is at the proper position.
The lens barrel may be completed by being slid for the fitting length of a and 6b and incorporated. The subsequent steps are the same as those described above.

Next, the configuration of the aperture unit 13 and the opening / closing mechanism of the aperture blades will be described in detail. In FIG. 9, reference numeral 131a denotes a diaphragm actuator. As the diaphragm actuator 131a, any actuator may be used as long as it generates a required torque for opening and closing the diaphragm blades. For example, a galvanometer or a stepping motor may be used.

The intermediate portion of the drive lever 131b is press-fitted and held on the output shaft of the actuator 131a. At both ends of the drive lever 131b, the connecting shaft 13
1b1 and 131b2 are formed respectively.

The connecting shaft 131b1 of the driving lever 131b
Is rotatably and radially fitted into a hole 131c1 formed in the first diaphragm blade (light shielding blade) 131c, whereby the drive lever 131b and the first diaphragm blade 131c are connected. The first diaphragm blade 131c is further formed with a guide groove 131c2 having a curved shape.
A guide shaft 131e1 provided on the base member (apparatus main body) of the aperture unit 13 is engaged with 31c2.

The connecting shaft 13 of the drive lever 131b
1b2 is a hole 13 formed in the second diaphragm blade 131d.
1d1 so as to be rotatable so that the driving lever 1
31b and the 2nd diaphragm blade 131d are connected. The second diaphragm blade 131d has another guide groove 1 having a curved shape.
31d2 is formed, and the guide groove 131d2 is formed.
The guide shaft 131e provided on the base member
2 are engaged.

Here, as shown in FIG.
31d1 and 131d2 each have an arc shape with a radius of curvature R, and are formed in an arc shape that is convex on the side of the light passage opening S formed by the two diaphragm blades 131c and 131d.

In the aperture unit 13 configured as described above, when the aperture actuator 131a is driven to rotate the drive lever 131b, the first aperture blade 131c and the second aperture blade 13 connected to the drive lever 131b.
The guides 1d are driven in the vertical direction in the optical axis orthogonal direction while being moved and guided by the engagement between the guide grooves 131c2 and 131d2 and the guide shafts 131e1 and 131e2. Thereby, both diaphragm blades 131
The opening area of the light passage opening S formed by c and 131d changes between the open state and the fully closed state, and the amount of light incident on the CCD through each group lens is adjusted.

FIG. 10 shows both diaphragm blades 131c and 131c.
d shows the movement trajectory of each part when driven between the open state and the fully closed state. Projection 1 of drive lever 131b
Each of the movement trajectories B and A of 31b1 and 131b2 has an arc shape centering on the rotation center O of the drive lever 131b and projecting toward the opposite side to the rotation center O.

In FIG. 10, 131 f is the diaphragm blade 1
The center position (the center of gravity of the opening area) of the light passage opening S when the 31c and 131d are driven between the open state and the fully closed state is shown. The center position 131f of the light passage opening S is the diaphragm blade 131c. , 131d are hardly moved during driving, and are maintained at a substantially constant position in a plane orthogonal to the optical axis.

The aperture unit 13 is positioned in the lens barrel such that the center position 131f substantially coincides with the optical axis of the lens barrel (or the photographing optical axis of the imaging device).

Here, the reason why the center position 131f of the light passage opening S is maintained at a substantially constant position when the diaphragm blades 131c and 131d are driven will be described with reference to FIG.

When the drive lever 131b rotates, a straight line L passing through the center position 131f of the light passage S (in this embodiment, the straight line L also passes through the rotation center O of the drive lever 131b) to the connecting shaft 131b2. Distance A is A1, A2,
A3 ... A6. On the other hand, the distance B from the straight line L to the connection shaft 131b1 is B1, B2, B3,.
And so on.

Further, from the straight line L, the second diaphragm blade 131
The distance a to the engagement position between the guide groove 131d2 and the guide shaft 131e2 changes as a1, a2, a3... a6. On the other hand, the first diaphragm blade 1
Guide groove 131c2 and guide shaft 131e1 of 31c
The distance b to the engagement position changes with b1, b2, b3... B6.

If the guide grooves 131d2, 131c2 are formed in a linear shape, the aperture blades 131c, 13c
1d moves up and down while swinging in the left and right directions in the figure around the connection shafts 131b1 and 131b2 and the guide shafts 131e1 and 131e2, respectively, and the center of the light passage S also moves (FIG. 18). reference).

However, in this embodiment, the distance Ai
(I = 1, 2, 3,... 6) and distance ai (i = 1, 2, 3,...)
6) and the distance Bi (i = 1, 2, 3,... 6)
And the distances bi (i = 1, 2, 3,..., 6) are set such that the curved shapes of the guide grooves 131d2, 131c2 are constant.
Are the connecting shafts 131b1 and 131b2 and the guide shaft 1
It does not swing in the left and right directions in the figure (with a shift in the left and right directions) around the center 31e1 and 131e2, but moves in the up and down direction while maintaining the same posture. Therefore, when the diaphragm blades 131c and 131d are driven between the open state and the fully closed state, the center position 131f of the light passage opening S is always at a substantially constant position (on the lens optical axis or the photographing optical axis position). Will be maintained.

Therefore, the amount of light around the optical axis with respect to the CCD can be made uniform, and an image without uneven brightness can be photographed regardless of the aperture state. It turns out that it is located in.

In the above embodiment, the guide shafts 131e1 and 131e2 are provided on the base member,
Although the case where the guide grooves 131c2 and 131d2 are provided in c and 131d has been described, a guide groove may be provided in the base member and a guide shaft may be provided in the diaphragm blade.

In the above embodiment, the drive lever 13
1b, connecting shafts 131b1 and 131b2 with aperture blades 13
Although the case where the holes 131c1 and 131d1 are provided in 1c and 131d has been described, the holes may be provided in the drive lever and the connecting shafts may be provided in the aperture blades.

In this embodiment, two diaphragm blades 1 are used.
A guide groove 131 having a curved shape is formed on both of the guide grooves 31c and 131d.
Although the case where c2 and 131d2 are provided has been described, a curved guide groove may be formed on one of the aperture blades, and a straight guide groove may be formed on the other.

Further, in this embodiment, the lens barrel for a video camera has been described. However, the present invention can be applied to still image cameras and other image pickup devices, and lens barrels for them.

[0083]

As described above, according to the present invention,
Since the guide groove for guiding the movement of the light-shielding blade is formed in a curved shape in a plane orthogonal to the optical axis, the posture of the driven light-shielding blade and the posture and The degree of freedom in controlling the position can be increased.

By setting the curved shape of the guide groove so that the center of the light passage opening (the center of gravity of the opening area) is maintained at a substantially constant position in a plane orthogonal to the optical axis when the light shielding blade is driven, The movement of the center position of the light passage opening when the light shielding blade is driven can be substantially eliminated. For this reason, by mounting this light amount adjusting device on a lens barrel or an imaging device and making the center position of the light passage substantially coincide with the lens optical axis or the photographing optical axis, it is possible to obtain a uniform peripheral light amount, It is possible to perform imaging without uneven brightness regardless of the light amount adjustment state.

When the light-shielding member is driven, the curved shape of the guide groove is defined by the distance from the straight line passing through the center of the light passage opening in the plane orthogonal to the optical axis to the connection between the light-shielding member and the drive lever, and from the straight line to the guide. If the sum of the distance to the engagement position with the guide shaft in the groove is set so as to maintain a substantially constant value, the light-shielding blade is swung about the connection portion and the guide shaft in a plane orthogonal to the optical axis. It is possible to move the light-shielding blades in opposite directions without moving the light-shielding blades, and it is possible to substantially eliminate the movement of the center position of the light passage opening when the light-shielding blade is driven.

Further, according to the present invention, in the connecting portion between the light-shielding blade and the drive lever, the connection shaft provided on one of the light-shielding blade and the drive lever is rotatably fitted into a hole formed on the other. It is suitable for a light amount adjusting device of a type in which one light shielding blade can move and guide the light shielding blade by a pair of guide shafts and guide grooves, thereby realizing a small light amount adjusting device with good optical performance. be able to.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a lens barrel for a video camera having an aperture unit according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the lens barrel.

FIG. 3 is a configuration diagram of a mold slide of a front lens barrel constituting the lens barrel.

FIG. 4 is a rear view of the front lens barrel.

FIG. 5 is a configuration diagram of a mold slide of a rear barrel that constitutes the lens barrel.

FIG. 6 is a front view of the rear barrel.

FIG. 7 is an exploded perspective view of the lens barrel.

FIG. 8 is a diagram showing an engagement state between the front lens barrel and an intermediate frame.

FIG. 9 is a configuration diagram (view in the optical axis direction) of the aperture unit.

FIG. 10 is a diagram illustrating a movement locus of each component in the aperture unit.

FIG. 11 is a diagram for explaining a relationship between a rotation locus of a connection portion of a drive lever in the aperture unit and a shape of a guide groove.

FIG. 12 is a sectional view of a conventional lens barrel for a video camera.

FIG. 13 is a block diagram of an electric circuit of a conventional lens barrel for a video camera.

FIG. 14 is a configuration diagram of a conventional diaphragm device.

FIG. 15 is a configuration diagram of a conventional diaphragm device (open state).

FIG. 16 is a configuration diagram of a conventional aperture device (fully closed state).

FIG. 17 is a side view of a conventional diaphragm device.

FIG. 18 is a view for explaining the movement trajectory of each component and the movement of the center of the light passage opening in the conventional diaphragm device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st group lens 2 Variator group lens 3 Afocal group lens 4 Focusing group lens 5 Front lens barrel 5a Shading line 5b Fixed screw lower hole 5c, 5d Left and right sliding hole 5e, 5f Right and left regulation reference rib 5g 5h Reference hole 5i, 5j, 5k Lock groove 6a, 6b Guide shaft 7 Rear barrel 7a Contact reference surface 7b Low-pass filter holding unit 7c CCD holding unit 7d, 7e Reference hole 8 V moving ring 8a sleeve 8b U groove 9 RR moving ring 9a sleeve 9b U groove 10 PZ motor 10a screw shaft 10b holding member 11 AF motor 11a screw shaft 11b holding member 12 intermediate frame 12a reference positioning hole 12b steady rest long hole 12c, 12d, 12e locking portion 13 aperture unit 131a Blade drive actuator 131b Over 131b1,131b2 connecting shaft 131c first diaphragm blade 131d center of the second diaphragm blade 131c1,131d1 hole 131c2,131d2 guide groove 131e1,131e2 guide shaft portion 131f light passing port S (the center of gravity of the opening area)

Claims (10)

[Claims] 1. An apparatus which moves in a direction orthogonal to an optical axis with respect to an apparatus main body in opposite directions to change an opening area of a light passage port.
The light-shielding blades and the light-shielding blades are connected to each other to rotate,
A drive lever for driving the two light-shielding blades, and moving the light-shielding blade by engaging a guide shaft provided on one of the apparatus body and the light-shielding blade with a guide groove formed on the other. In the light amount adjusting device for guiding, at least one of the guide grooves for moving and guiding the two light shielding blades is formed in a curved shape in a plane orthogonal to the optical axis. Light control device. 2. A movement trajectory of a connecting portion between the drive lever and the light-shielding member in accordance with the rotation of the drive lever has an arc shape that is convex on a side opposite to a rotation center side of the drive lever. The light amount adjusting device according to claim 1, wherein the curved guide groove is formed in an arc shape that is convex toward the light passage opening side. 3. The curved shape of the guide groove is set such that a center position of the light passage opening is maintained at a substantially constant position in a plane orthogonal to an optical axis when the light shielding blade is driven. 3. The light amount adjusting device according to 1 or 2. 4. A connecting portion between the light-shielding blade and the drive lever, wherein a connection shaft provided on one of the light-shielding blade and the drive lever is rotatably fitted into a hole formed on the other. The light amount adjusting device according to any one of claims 1 to 3, wherein the light shielding blade is moved and guided by a pair of guide shafts and guide grooves for one light shielding blade. 5. The light-shielding blade according to claim 1, wherein the light-shielding blade moves in the plane orthogonal to the optical axis without swinging about the connecting portion and the guide shaft. Light control device. 6. When the light shielding member is driven, a distance from a straight line passing through the center of the light passage opening in a plane orthogonal to an optical axis to a connecting portion between the light shielding member and the driving lever, and the guide groove from the straight line 6. The curved shape of the guide groove is set such that the sum of the distance to the engagement position with the guide shaft at the time of maintaining a substantially constant value. Light control device. 7. A lens device comprising the light amount adjusting device according to claim 1. Description: 8. The lens device according to claim 7, wherein a center position of the light passage opening substantially coincides with a position of a lens optical axis. 9. An image pickup apparatus comprising the light amount adjusting device according to claim 1. Description: 10. The imaging device according to claim 9, wherein a center position of the light passage opening substantially coincides with a position of an imaging optical axis.