JP2583855Y2 - Light control device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light amount control device, and more particularly to a light amount control device used for a camera, a video camera, etc., which can prevent a load change due to contact between diaphragm blades.

[0002]

2. Description of the Related Art In recent years, as a light amount control device used for a camera, a video camera, or the like, a method of controlling a light amount by adjusting an aperture opening using two aperture blades for cost reduction and miniaturization has been generalized. ing.

FIG. 5 is an exploded perspective view of an iris diaphragm which is a light amount control device in a conventional video camera.

[0005] As shown in FIG. 5, a motor 105 is provided below the base plate 104 on the imaging surface side (P direction), and the motor 10 is provided in a recess formed below the base plate 104.
Drive lever 125 integrally attached to the rotor 5
Are stored in a state of being urged in a predetermined direction by a coil spring 124. The aperture blade 103 is a concave portion 104 having an appropriate depth and formed on the object side of the main plate 104.
The ribs 117a, 117b, and 117c, which are the rib groups 117 protruding at a, and the ribs 107a and the ribs 1, which are the rib groups 107 protruding on the imaging surface side of the holding plate 101.
07b and the rib 107c are slidably held so as to be arranged at an appropriate position with respect to the optical axis O.

Similarly, the diaphragm blade 102 is also
The ribs 118a, 118b, and 118c, which are a group of ribs 118 protruding from the concave portion 104a, and the rib 1 which is a group of ribs 108 protruding toward the imaging surface side of the holding plate 101
08a, the rib 108b, and the rib 108c, the optical axis O
And is slidably held so as to be disposed at an appropriate position with respect to. Also, the aperture blade 103 and the aperture blade 10
Guide hole 115, guide hole 1 provided in each of 2
A pin 119 and a pin 120 projecting from the main plate 104 are engaged with the aperture plate 12, respectively.
The shaft hole 116 of the diaphragm blade 102 and the shaft hole 111 of the diaphragm blade 102
Each of the pins 12 provided on the drive lever 125
2. The pin 123 is inserted. Thus, the drive lever 1 that is driven in conjunction with the rotor of the motor 105
The rotation of the aperture blade 25 causes the aperture blade 103 and the aperture blade 10 to rotate.
Numerals 2 slide in the vertical direction facing each other in a plane perpendicular to the optical axis O.
3 and the aperture adjusting section 109 of the aperture blade 102 make it possible to realize a desired aperture.

[0006] At this time, usually, the aperture adjusting section having a semicircular shape of each aperture blade is provided with a small aperture (a large Fno.).
Compared to the time of large drawing (Fno. Is small), Fno. The swelling portions (small-aperture adjusting portions) 110 and 114 are provided so that the rate of change of does not become extremely large.

[0007]

By the way, in general, when the aperture is stopped down, the lens performance (aberration, resolution, etc.) is good because the light rays irregularly reflected in the lens frame can be cut and the depth of field increases. Is known to be.

Therefore, in lens design, the minimum Fn
o. The design focuses on improving the lens performance at the time. At this time, it is general that the design of the stop is made circular in order to simplify various calculations at the time of design. Therefore, the minimum Fno. If a configuration is adopted in which the aperture diameter at the time (hereinafter referred to as an open diameter) is determined, light rays that were not taken into consideration at the time of designing the lens pass through this portion, resulting in deterioration of the lens performance.

Therefore, the holding plate 104 and the main plate 101
It is generally known that at least one of the above has a size corresponding to the open diameter and determines the open diameter at a circular opening.

[0010] In recent years, there has been a strong demand for small and lightweight users, and there is also a need for miniaturization of lens units mounted on cameras and video cameras. A design has been made. However, at present, the above-mentioned holding plate 1
01 or the determination of the open diameter at the main plate 104 prevents this. Hereinafter, this will be described.

FIG. 6 is a cross-sectional view of a main part of the iris diaphragm shown in FIG. 5, viewed from a direction perpendicular to the optical axis, to show the relationship between the iris diaphragm and the front and rear lenses in the lens unit. .

Generally, a lens is generally present before and after the iris diaphragm. Now, assume that the lens on the subject side is a lens F and the lens on the imaging surface side is a lens B. Actually, although not shown, each lens is supported by a lens frame and held so as to be arranged at an appropriate position in the optical axis direction.

[0013] In this case, the determination of the open diameter φD is determined by the main plate 104.
Of the diaphragm blade 103 (FIG. 5).
With reference to the position of the reference B), it can be seen that the lens B cannot approach the diaphragm blade 103 because it interferes with the main plate 104. The same applies to the case where the opening diameter is determined by the holding plate 101, and the lens F cannot approach the diaphragm blade 103 in order to avoid interference with the holding plate 101.

Therefore, even if an attempt is made to design a lens in which the distance t 'between the lens F and the lens B is reduced in order to reduce the size, the thickness cannot be shorter than the thickness of the iris diaphragm in the optical axis direction.

Of course, if the outer shape of the lens is made smaller than the openings of the base plate and the holding plate, it is possible in principle to make the lens closer to the aperture blade 103, but the prerequisites increase and the load at the time of optical design is increased. Not really.

By the way, as shown in FIG. 6, as a general means for determining the open diameter by the base plate 104, as shown in Japanese Utility Model Laid-Open No. 1-75221, unnecessary The opening rib portion 128 is left except where the open diameter is determined to prevent internal reflection, and the imaging screen side near the opening 129 of the main plate 104 is greatly rounded to form the main plate concave portion 104b. This makes it possible to bring the lens B closer to the diaphragm blade 103, but the thickness in the optical axis direction and the length in the optical axis direction of the opening rib portion 128 are restricted by the processing of the base plate
It is difficult to say that by increasing the diameter of b and reducing the outer diameter of the lens, the lens B approaches the diaphragm blade 103 and the distance between the lens F and the lens B decreases. Therefore, from the above, conventionally,
1. If the aperture diameter is determined at the aperture blades in an attempt to reduce the distance between the lenses disposed before and after the iris diaphragm, unnecessary light rays that were not taken into account at the time of optical design are guided to the imaging screen, and the optical performance of the lens deteriorates.

2. If the open diameter is determined by the base plate or the holding plate so as to block unnecessary light rays, the distance between the lenses before and after the iris diaphragm becomes large, and the lens unit becomes large.

There is a problem.

The present invention has been made in view of such a problem, and it is possible to shield unnecessary light beams which are not taken into consideration at the time of optical design with a simple configuration, and to shorten the distance between lenses disposed before and after the light amount control device. It is possible and positive
It is an object of the present invention to provide a light amount control device that performs a reliable and stable operation .

[0020]

In order to achieve the above-mentioned object, a light quantity control device according to the present invention is provided so as to be capable of a predetermined relative displacement, and in the course of the relative displacement, is stopped down from an open stop state. a plurality of shutter blades which an aperture adapted to define in the state, have a opening for defining the iris diameter in an open state is provided separately from this plurality of shutter blades, the plurality of diaphragm blades Provided between and
A thin plate-shaped light shielding member having a thickness equivalent to that of the aperture blade .

[0021]

In the present invention, the aperture diameter in the open state is defined by the thin plate-shaped light shielding member.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing a main part of a light quantity control device according to a first embodiment of the present invention.

In the first embodiment, the basic structure is the same as that of the above-mentioned conventional example, and the thin plate-shaped light-shielding portion which is not provided in the conventional example.
It is characterized in that a spacer 3 as a material is provided between the diaphragm blade 2 and the diaphragm blade 4.

As shown in the figure, the surface of the base plate 5 disposed on the photographing screen side (P direction in the figure) on the subject side (Q direction in the figure) is appropriately formed by a side wall portion 38 of the base plate 5. A concave portion 37 having an appropriate depth is formed. A circular opening 26 is formed at the center of the concave portion 37, and two support pins 28 and 29 project from both lower sides of the opening 26. Notches 27, 30, and 31 having a depth slightly shorter than the depth of the side wall portion 38 are provided at the upper center and both lower side portions of the side wall portion 38. In addition,
The spacer 3 is provided in the concave portion 37 as described later.

On the other hand, a motor 6 is disposed on the lower photographing screen side of the base plate 5, and a concave portion formed further below the concave portion 37 is rotatably supported by a rotor of the motor 6. A drive lever 7 is provided. A drive pin 34 is provided at one end of the drive lever 7 and a drive pin 36 is provided at the other end.
Are protruded toward the subject side, respectively. further,
A coil-shaped spring 35 is disposed on the shaft of the drive lever 7, and the drive pin 34 is urged in a downward direction. The drive pin 34 is inserted into a shaft hole 24 of the aperture blade 4 described later.
Is inserted into a shaft hole 15 of the aperture blade 2 described later.

As shown in the front view of FIG. 2 (a), the spacer 3 has an extremely thin open opening determining portion 16 formed at the center thereof at a position facing the opening 26 of the base plate 5. It is a plate-shaped member, and its outer shape does not interfere with the inner wall surface 38a of the side wall portion 38 so as to be inserted into the concave portion 37 of the base plate 5. Stoppers 17, 18, 1 engaging with the notches 27, 30, 31 of the side wall 38 are provided at the center and lower side edges on the upper semicircular arc of the spacer 3.
The spacers 3 are disposed in the recesses 37 with a slight gap, and are fixed to the base plate 5 by bonding or the like. Also,
Two engagement holes 20 and 21 are formed near the lower side edges of the open opening determination section 16, respectively.
The spacers 3 are positioned in a plane perpendicular to the optical axis by the support pins 28 and 29 being fitted.

A diaphragm blade 4 having the same shape and function as the conventional example is slidably disposed between the spacer 3 and the concave portion 37 of the base plate 5. The aperture blade 4 has an aperture adjustment unit 22 having a small aperture adjustment unit 25 similar to the prior art.
Are formed. A vertically long guide hole 23 is formed in the vicinity of one side of the opening adjusting portion 22, and a shaft hole 24 is formed in a tip of a lower projecting portion of the diaphragm blade 4. I have. A drive pin 34 protruding from one end of the drive lever 7 is inserted through the shaft hole 24.
The support pin 28 of the base plate 5 is inserted through the guide hole 23. Accordingly, the aperture blade 4 slides vertically in a plane perpendicular to the optical axis O in conjunction with the vertical swing operation of the drive pin 34 due to the rotation of the motor 6. ing. When the diaphragm blade 4 moves upward, the opening adjustment unit 22 moves the base plate 5.
Is arranged at a position opposed to the opening 26.

On the other hand, an aperture blade 2 having the same shape and function as the conventional example is slidably disposed between the spacer 3 and a holding plate 1 described later. The aperture blade 2 is formed with a semicircular aperture adjusting section 12 having a small aperture adjusting section 13 similar to the conventional example. A vertically long guide hole 1 is located near the other side of the opening adjusting portion 12.
4 and a shaft hole 15 is formed at the tip of the lower projecting portion of the diaphragm blade 2. And the shaft hole 1
5 includes a drive pin 3 protruding from the other end of the drive lever 7.
6 and the support pin 29 of the base plate 5 is inserted into the guide hole 14. As a result, the aperture blade 2 is driven by the drive pin 36 by the rotation of the motor 6.
The guide hole 14 interlocks with the vertical swing motion of
To slide in the vertical direction. Then, when the diaphragm blade 2 moves downward, the opening adjusting section 12 is arranged at a position facing the opening section 26 of the base plate 5. The diaphragm blade 2 and the diaphragm blade 4 move up and down in directions facing each other by the rotation of the drive lever 7.

The holding plate 1 is provided on the side surface 38 b of the base plate 5.
And the engaging portions 8, 9 provided at the center of both side edges are snap-fitted to the engaging portions 32, 33 provided at positions opposite to the engaging portions 8, 9 on both side edges of the base plate 5. And a predetermined space is formed between the bottom plate 5 and the concave portion 37. An opening 11 is formed at the center of the holding plate 1 at a position facing the opening 26 of the base plate 5. Further, grooves 1a and 1b each having a partial shape of a circular arc of rotation of the drive pins 34 and 36 of the drive lever 7 are formed in opposite lower sides of the opening 11 at positions facing each other. The drive pin 36 is provided in the groove 1a, and the drive pin 34 is provided in the groove 1b.
Are configured so as not to hinder the swing operation of these support pins due to the contact.

Here, the details of the spacer 3 will be described.

By the way, the gap between the two diaphragm blades is about 0.2 mm in nominal size, and in reality, 0.03 to
In general, it is designed to be arranged so as to vary by about 0.37 mm. Therefore, if the thickness of the spacer 3 is also about 0.2 mm, there is no optically practical problem. In addition, if the material of the spacer 3 is metal, it is easy to realize the above-described thickness of about 0.2 mm, so that no problem will be caused even if it is adopted. In addition, any resin material can be used as long as it can secure appropriate strength.

The material of the base plate 5 and the holding plate 1 may be a metal material or a resin. Further, the material of the aperture blade is desirably polyester, but may be a metal material.

FIG. 3 is an enlarged cross-sectional view of a central portion of the light quantity control device of the first embodiment and main portions of the photographing lenses disposed before and after the light quantity control device as viewed in a direction perpendicular to the optical axis. It is.

In the figure, the lens indicated by F indicates the lens F on the subject side, and the lens indicated by B indicates the lens B on the imaging surface side. Each of the lenses B and F is supported by a lens frame (not shown), and is held at an appropriate position in the optical axis direction.

As described above, a circular open opening determining section 16 is formed at the center of the spacer 3, and the diameter of the open opening determining section 16 is D as shown in FIG. .

According to the first embodiment, the definition of the open opening diameter can be realized in the spacer 3 having a small thickness.
It is possible to set the openings 26 and 11 at large to escape to the outside of the lenses F and B. Accordingly, the distance t 'between the lens F and the lens B can be reduced, and the camera can be downsized.

Next, a second embodiment of the present invention will be described.

FIG. 4 is an exploded perspective view of a main part showing the light quantity control device of the second embodiment.

In the second embodiment, the arrangement of each member is the same as that of the first embodiment, but the shape of each part is the same as that of the first embodiment.
This is different from the embodiment.

As shown in the figure, the base plate 45 disposed on the side of the photographing image plane P is a short cylindrical member in which a concave portion 78 having an appropriate depth is formed by the side wall 72 on the side of the subject Q. It is. A circular opening 66 having a protruding notch 67 is formed in the center of the recess 78,
Two support pins 69, 7 are provided on both lower sides of the opening 66.
0 is protruding. Note that a spacer 43 is provided in the concave portion 78 as described later.

On the other hand, a motor 46 is provided on the side of the bottom plate 45 in the direction of the lower imaging plane P. The motor 46 is fixed to the base plate 45 by screws 76 at the tip of a flange 75 formed integrally with the motor 46. Further, a drive arm 77 that is pivotally supported by the motor 46 and that rotates in conjunction with the rotation of the motor 46 is disposed at the tip of the motor 46. Further, a drive pin 74 protruding toward the Q direction is provided at a tip end of the drive arm 77. The swing operation of the drive pin 74 is performed in the protruding notch 67. The drive pin 74 is connected to an aperture blade 44 described later.
Are inserted into the guide holes 64 provided in the
3 further presses the holding plate 41 through the groove 60
Is inserted into the guide hole 56 provided in. on the other hand,
Although not shown, an urging force may be applied to the drive pin 74 by a spring having the same function as the spring 35 in the first embodiment.

The spacer 43 is provided with an open opening determining portion 58 at a position in the center opposite to the opening 66 of the base plate 45.
Is formed on the side wall 72 so as to fit into the recess 78 of the base plate 45.
Are formed along the inner wall surface 73. The spacer 43 is fixed by bonding, welding or the like so as to provide a predetermined space with the recess 78. A circular engagement hole 6 is formed on one side below the open opening determination portion 58.
1, and elongated guide holes 59 are formed on the other side, respectively.
9, 70 are fitted. In addition, the above-mentioned open opening determination unit 5
A groove 60 having a partial arc shape of the rotation arc of the drive pin 74 is provided below the drive pin 8, and the drive pin 74 is inserted therethrough.

The spacer 43 and the concave portion 7 of the base plate 45
The diaphragm blade 44 is slidably disposed between the diaphragm blade 8 and the diaphragm blade 8. The diaphragm blade 44 has a substantially semi-circular tip at the tip and rotates about a support pin 69 of the base plate 45 inserted into a shaft hole 65 provided at the base. An opening adjusting section 62 having a small stop adjusting section 63 is formed on the inner diameter surface of the semicircular arc at the tip end. A vertically long guide hole 64 is formed at the base end side of the arm from the opening adjusting portion 62, and the drive pin 74 is fitted therein. Thereby, the diaphragm blade 44 interlocks with the vertical swing operation of the drive pin 74 due to the rotation of the motor 46, and the axis of the aperture blade 65 in the plane perpendicular to the optical axis O in FIG. It slides in the direction of arrow R.

On the other hand, an aperture blade 42 is slidably disposed between the spacer 43 and a pressing plate 41 described later. The diaphragm blade 42 is similar to the diaphragm blade 44 described above.
A shaft hole 57 having a substantially semicircular arc at the distal end and provided at the proximal end
Is rotated about the support pin 70 of the base plate 45 inserted into the base plate 45. An opening adjustment section 54 having a small aperture adjustment section 55 is formed on the inner diameter surface of the semicircular arc at the tip end. Further, a vertically long guide hole 56 is provided on the base end side of the arm with respect to the opening adjusting portion 54.
And the drive pin 74 is fitted therein.
As a result, the aperture blade 42 is interlocked with the vertical swing operation of the drive pin 74 due to the rotation of the motor 46, and the axis of the aperture hole 57 in the plane perpendicular to the optical axis O in the drawing. It slides in the direction of arrow U. The diaphragm blade 42 and the diaphragm blade 44 rotate in the directions facing each other by the rotation of the drive arm 77.

The holding plate 41 is a disk-shaped member having an opening 51 in the center, and a positioning hole 53 provided on one side edge and a long hole 52 provided on the other side edge are formed by the base plate. 45 is engaged with and fixed to engaging portions 71 and 68 provided at positions opposing the holes 53 and 52 on the side wall portion 72.

In the second embodiment, as in the first embodiment, the opening diameter can be determined by the opening determining section 58, so that the openings 66 and 51 in the base plate 45 and the holding plate 41 can be set large. This makes it possible to reduce the lens interval.

In the iris diaphragms shown in the first embodiment and the second embodiment, in order to slidably hold the respective diaphragm blades at predetermined positions, the surface of the holding plate on the image sensor side and the space plate are arranged. Since the two surfaces perpendicular to the optical axis and the surface of the main plate on the object side are in surface contact with the aperture blade, the load on the aperture blade is large.

However, the friction, which is a load acting during driving of the diaphragm blade, is always kept at a constant level by processing each of the above-mentioned surfaces which come into contact with the diaphragm blade so as not to interfere with the antireflection uneven surface of the diaphragm blade surface. Act on. Therefore, by properly selecting the torque constant (torque generated per unit current: g.mm/A) of the motor as the drive source,
It can be driven smoothly.

In order to reduce the friction, a holding plate,
Alternatively, it can also be realized by projecting a rib or the like from the main plate toward the diaphragm blade to reduce the contact area with the diaphragm blade.
Further, a protrusion may be formed on the space plate by etching, painting, press working, or the like on the contact surface side with the diaphragm blade. Hereinafter, the protrusion will be described.

FIG. 2A is a front view of the spacer 3 as viewed from the subject side, and FIG. 2B is an enlarged cross-sectional view of a main part of the spacer 3 as viewed from below. .

As can be seen from FIG. 2B, convex and concave portions are continuously formed on the front and back surfaces of the spacer 3 by etching, painting, or the like to form an uneven surface. It plays a role of reduction. That is, the ridges hold the aperture blades 2 and 4 so as to be arranged at appropriate positions with respect to the optical axis.

FIG. 2C is a cross-sectional view showing an example in which the protrusion is formed by press working, and has the same function as the protrusion by etching and painting.

It is generally known that, when the aperture is stopped down, lens performance (aberration and resolution) is improved because light rays irregularly reflected in the lens frame can be cut and the depth of the subject increases.

Therefore, in the lens design, the minimum Fn
o. Often, the design is focused on improving the lens performance at the time. At this time, it is general that the design of the stop is made circular in order to simplify various calculations at the time of design.

By the way, usually, the aperture adjusting section having the semicircular shape of each aperture blade has a small aperture (large Fno.).
At the time of the large drawing (the Fno. Is small).
A swelling portion (small aperture adjusting portion) is provided so that the rate of change of does not become extremely large.

Therefore, the minimum Fno. If a configuration is adopted in which the aperture diameter at the time (hereinafter referred to as an open diameter) is determined, light rays not taken into consideration at the time of lens design pass through this portion, leading to deterioration of the lens performance.

However, in each of the first and second embodiments, since the opening diameter is determined by the spacer, the opening diameter of the diaphragm can be realized in a perfect circular shape. It is possible to block the incidence of unnecessary light rays that are not taken into account when designing the lens.

In the first and second embodiments,
Although the iris diaphragm of the video camera has been described, the present invention can be applied to other light amount control means, shutters, and the like.

Even if no spacer is interposed between the two diaphragm blades, the same effect can be obtained even if the diaphragm blade is arranged between the diaphragm blade and the holding plate or between the diaphragm blade and the ground plate. Needless to say.

Further, the present invention can be applied not only to the light amount control device having two diaphragm blades but also to a mechanism having three or more diaphragm blades.

Although omitted in the first and second embodiments, an ND filter may be attached to the aperture blade to avoid the diffraction phenomenon at the time of small aperture.

As described above, according to the first and second embodiments, the distance between the conventional diaphragm blades in the optical axis direction is 0.03 m.
Since the thickness of the plate varies from 0.3 to 0.37 mm, a plate member capable of maintaining the thickness is interposed between the two diaphragm blades, so that the contact between the diaphragm blades can be completely achieved without impairing the optical function of the light amount control device. To avoid sticking while the aperture blades are being driven.
Prevent unstable movement of the aperture blade due to kissing etc.
This allows accurate and stable aperture control.
Wear. Therefore, it is possible to realize a light amount control device that appropriately follows a change in the subject light, does not cause hunting, flickers the subject, and does not require a long time to obtain an appropriate exposure amount.

[0064]

As described above, according to the present invention, unnecessary light rays which are not considered in the optical design can be shielded with a simple structure, and the distance between the lenses disposed before and after the light quantity control device can be shortened. Will be possible . In addition, it is the same as a shading blade
A thin plate-shaped light-shielding member having a thickness of
To completely avoid contact between the aperture blades
And light blocking due to stick-slip etc. while the diaphragm blades are driving
Prevents unstable movement of the blades and ensures accurate and stable
Aperture control can be performed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part showing a light amount control device according to a first embodiment of the present invention.

2A is a front view of the spacer in the first embodiment as viewed from the subject side, FIG. 2B is an enlarged cross-sectional view of a main part of a part of the cross section of the spacer viewed from below, and FIG. The principal part expanded sectional view which showed another example of the protrusion formation of the said spacer.

FIG. 3 is an enlarged cross-sectional view of a main part of the light amount control device according to the first embodiment, and main components of a photographing lens disposed before and after the light amount control device, as viewed in a direction perpendicular to the optical axis.

FIG. 4 is an exploded perspective view of a main part showing a light amount control device according to a second embodiment of the present invention;

FIG. 5 is an exploded perspective view of an iris diaphragm as a light amount control device in a conventional video camera.

FIG. 6 is a cross-sectional view of a main part showing the relationship between the iris diaphragm shown in FIG. 5 and front and rear lenses in the lens unit, as viewed from a direction perpendicular to the optical axis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Holding plate 2, 4 ... Aperture blade 3 ... Spacer 5 ... Ground plate 6 ... Motor 7 ... Drive lever 16 ... Opening opening determination part

Claims (1)

(57) [Scope of request for utility model registration] An apparatus is provided so that a predetermined relative displacement is possible,
In the process of the relative displacement, a plurality of light-shielding blades are provided so as to define an aperture aperture in a state where the aperture is narrowed from an open aperture state, and the plurality of light-shielding blades are separately provided, and the aperture diameter in the open state is reduced. possess an opening for defining said plurality of diaphragm blades
It is provided between the roots, and has a thickness equivalent to that of the diaphragm blade.
And a thin plate-shaped light shielding member.