JP2002131802A - Diaphragm mechanism for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm mechanism for a camera with simple structure capable of forming a circular aperture at only minimum opening condition of the diaphragm. SOLUTION: A drive ring 12 is rotated by a rotor 10 of a stepping motor through a gear 11. Seven closing blades 14 are fastened on a base plate 1 by pins 14a, and a pin 14b is fitted in a cam groove 12a of the drive ring 12. An ND filter 13b is attached on a light limiting member 13 supported by a pivot 1q so as to cover an aperture section 13a, and a pin 13c is fitted in the cam groove 12a of the drive ring 12. If the drive ring 12 is rotated in clockwise direction, the opening is reduced by the seven closing blades 14. After the minimum opening condition controlled by the closing blade 14 is attained, the closing blade 14 is stopped, and the only light limiting member 13 is activated, and then the aperture section 13a having an aperture smaller than that in the minimum opening condition is inserted into an optical path.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aperture mechanism for a camera capable of suitably controlling the amount of a subject reaching a film, a CCD element, or the like during photographing.

[0002]

2. Description of the Related Art As a diaphragm mechanism for a camera, a movable light amount limiting member having one or two or more circular openings smaller in diameter than an exposure opening is widely used. The aperture is selectively inserted into the photographing optical path, and the aperture is changed so that the aperture of the aperture can be changed around the optical axis by simultaneously operating a plurality of aperture blades. There is. The former aperture mechanism is excellent in that a perfect circular aperture can be obtained.However, when trying to obtain a plurality of apertures having different diameters, the entire mechanism becomes large, and a small camera is not suitable. Sometimes it is difficult to adopt.

[0003] In the latter diaphragm mechanism, a drive ring that rotates about an optical axis rotates three or more diaphragm blades simultaneously in the same direction. The configuration is such that each diaphragm blade is rotatably attached to the main plate, and pin-slot connection to the drive ring (connection between pin and cam groove (long hole with cam shape))
It was done. Such an aperture mechanism is characterized in that an aperture having a relatively circular shape can be obtained continuously or in multiple stages, and the more the number of aperture blades, the closer to a circular shape. . However, if the number of diaphragm blades is increased, the number of parts and the number of assembling steps are increased, which causes a problem in terms of cost. The present invention relates to an improvement of such a camera aperture mechanism.

[0004]

By the way, this kind of diaphragm mechanism is characterized in that diaphragm apertures having different diameters can be formed relatively circular as described above. However, since the number of aperture blades is large, even if relatively uniform accuracy is obtained in the part processing stage, variations in the shape and area of each aperture opening may occur in accuracy. Such a variation is relatively not a problem when the aperture is large, but becomes more problematic as the aperture becomes smaller.

In the case of this type of aperture mechanism, the smaller the aperture, the more the aperture blades enter the exposure aperture, so that the attitude of each aperture blade becomes unstable, It is difficult to stably obtain an appropriate aperture. In order to prevent such a situation, it is known that all the diaphragm blades are arranged between the other two diaphragm blades. Then, if the aperture is made smaller than a predetermined size, the tip of each aperture blade warps or interferes with other aperture blades, making control impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. It is an object of the present invention to provide a driving ring in which a plurality of aperture blades are simultaneously rotated in the same direction so that different apertures are formed. A diaphragm mechanism for controlling a plurality of diaphragm apertures, wherein the diaphragm aperture with the smallest aperture is obtained by a light amount limiting member having a circular aperture, and a simple configuration of a camera diaphragm mechanism is provided. That is.

[0007]

In order to achieve the above-mentioned object, a camera diaphragm mechanism according to the present invention is pivotally attached to a main plate at equal angular positions around an optical axis, and simultaneously in the same direction. A plurality of diaphragm blades that rotate to change the diaphragm opening; and a light amount limiting member that is pivotally attached to the base plate and that can insert a circular opening smaller in diameter than the minimum diaphragm opening formed by the diaphragm blade into the optical path. And a drive ring arranged rotatably about the optical axis and connected to each of the aperture blades and the light amount limiting member in a fitting configuration with separate cam grooves and pins. The cam groove used to connect the drive ring and the aperture blade is formed such that the aperture blade is not substantially rotated when the drive ring inserts the opening of the light amount limiting member into the optical path. Like To.

In the aperture mechanism for a camera according to the present invention, a cam groove used for connecting the drive ring to the aperture blade and a cam groove used for connecting the drive ring to the light amount limiting member are provided. When the drive ring is formed, the processing requiring precision can be mainly concentrated on the drive ring, and the processing and assembly adjustment of the related parts can be easily performed as a whole.

In the camera aperture mechanism of the present invention, if an ND filter is attached to the opening of the light amount limiting member, the light amount can be greatly limited. Furthermore, the same effect can be obtained even with another configuration. That is, it is pivotally attached to the base plate, is connected to the drive ring by a fitting structure of a cam groove and a pin, and is driven only when the opening of the light quantity limiting member is inserted into the optical path. A cam groove used to connect the drive ring to the diaphragm blade; and a cam used to connect the drive ring to the light amount limiting member. The groove is formed so that the diaphragm blade and the light amount limiting member are not substantially rotated when the drive ring inserts the filter member into the optical path.

Further, in the camera aperture mechanism of the present invention, when the drive ring is rotated by a motor, both the aperture blade and the light amount limiting member, or a filter member in addition to them, is operated organically. A motor-operated aperture mechanism for the camera is obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to an embodiment shown in FIGS. The present embodiment can be applied to a camera using a film and a digital camera. However, in the description of the operation, description will be made on the assumption that the present invention is applied to a camera using a film. 1 is a plan view showing a state before photographing as viewed from the subject side, FIG. 2 is a cross-sectional view mainly for making the configuration of the motor easy to understand, and FIG. 3 is controlled by a plurality of aperture blades. FIG. 4 is a plan view showing a control state of a minimum possible opening, and FIG. 4 is a plan view showing a state where a circular opening is inserted in the state of FIG.

First, the configuration of this embodiment will be described with reference to FIGS. The base plate 1 of this embodiment is made of a synthetic resin, and has a circular opening 1a formed substantially at the center thereof.
Is an exposure opening for regulating the maximum aperture opening. On the back side of the base plate 1, as shown in FIG.
Are mounted on the main plate 1 by three screws 3 to form a blade chamber between the main plate 1 and the base plate 1. Although not shown, an opening larger than the above-mentioned opening 1a is also formed at a substantially central portion of the cover plate 2.
As shown in FIG. 1, a concave portion 1b is formed on the back side of the base plate 1, that is, on the surface on the blade chamber side, from the opening 1a in the radial direction.

Around the opening 1a, seven round holes 1c are formed at equal angular positions around the optical axis, and only one of them is provided with a reference numeral. In addition, two hooks 1d,
1e, four pedestals 1f, 1g, 1h, 1i and pedestal 1
f, 1g, two pins 1j, 1k
m. Further, on the back side of the main plate 1, three axes 1n, 1p, and 1q are provided as shown in FIG. 2, and two of the axes 1n, 1p are:
The tip is inserted into a hole provided in the cover plate 2.

In this embodiment, a stepping motor is used as a driving source. The stator is attached to the front side of the main plate 1. Therefore, next, the mounting configuration of the stator will be described. The stator is yoke 4,5
And the bobbins 8 and 9 around which the coils 6 and 7 are wound. The yokes 4 and 5 have two legs 4a, 4b, 5a and 5b each having a tip as a magnetic pole. , And fitting portions 4c and 5c formed on the base portion, and bobbins 8 and 9 are fitted to one of the leg portions 4a and 5a.

When attaching the yoke 4 to the main plate 1, first, in FIG.
Insert the tips of a and 4b into the groove formed in the cylindrical portion 1m. Then, the fitting portion 4c is fitted on the pin 1j and stopped by the hook portion 1d, thereby being fixed on the base portions 1f and 1h. Further, the other yoke 5 is attached to the right side of the cylindrical portion 1m, and is attached in the same manner as the above-described attaching method.
1i.

Next, the configuration inside the blade chamber will be described. First,
The rotor 10 of the stepping motor is magnetized to four poles, and its peripheral surface is connected to the legs 4a, 4b, 5 of the yokes 4, 5.
a, a permanent magnet 10a opposed to the tip surface of 5b;
A gear 10b is formed integrally with the permanent magnet 10a by outsert processing of a synthetic resin, and is rotatably attached to the shaft 1n of the main plate 1. Also,
A parent gear 11 for reduction is rotatably attached to the shaft 1p, and the parent gear meshes with a gear 10b of the rotor 10.

A drive ring 12 is disposed in the blade chamber, and slides on a guide surface (not shown) formed on the periphery of the main plate 1 so as to be rotatable about the optical axis. The drive ring 12 is formed with seven cam grooves 12a having the same shape, but reference numerals are given to only one of them. The drive ring 12 has another cam groove 12b having a different shape from those of the seven cam grooves 12a. Further, on a part of the outer periphery of the drive ring, the teeth 1 meshed with the child gear of the parent-child gear 11
2c.

A light amount limiting member 13 is rotatably mounted on the shaft 1q of the base plate 1 described above. The light quantity limiting member 13 is made of a metal thin plate, and has an ND filter 13b attached so as to cover the circular opening 1a. Since the ND filter 13b is affixed to the surface on the side of the base plate 1, the concave portion 1b is
To prevent the D filter 13b from being damaged, ND
It is formed along the operation path of the filter 13b. The pin 13c provided on the light quantity limiting member 13
Is fitted in the cam groove 12b of the drive ring 12 described above,
The pins and slots are connected.

In this embodiment, seven diaphragm blades 14 having exactly the same shape are provided, and they are arranged so as to be closer to the drive ring 12 than the light amount limiting member 13. However, in FIG. The illustration is omitted together with 13. Also, all the aperture blades 14 are stacked so as to be sandwiched between the other two aperture blades, and a pin 14a is provided on one surface.
And the other side has a pin 14b,
a is rotatably fitted into the hole 1c of the main plate 1. The pin 14b is fitted in the cam groove 12a of the drive ring 12, and is connected to a pin and a slot. Therefore,
When the drive ring 12 rotates, the seven diaphragm blades 14
The pins 14a can be simultaneously rotated in the same direction about the pins 14a. In FIG. 1, reference numeral is assigned to only one diaphragm blade.

Next, the operation of this embodiment will be described. FIG.
Shows a state before photographing is performed. Hereinafter, with respect to the rotor 10 and the drive ring 12, the position in FIG. 1 is referred to as an initial position. At this time, the light amount limiting member 1
Reference numeral 3 denotes an opening 1 by a cam groove 12b of the drive ring 12.
a has been rejected. The seven aperture blades 14 have the opening 1a fully opened (maximum diameter). In such a state of FIG. 1, when the release button is pressed,
Before the opening and closing operation of the shutter blade is performed, the control condition by the aperture is determined in accordance with the subject light. Then, when it is determined that the image is taken at the maximum aperture, the coils 6,
7 is not energized and the shutter blades are opened and closed in this state.

When an image is taken with an aperture smaller than the maximum aperture, the coils 6 and 7 are energized and the rotor 10 is rotated clockwise by a predetermined number of steps. Therefore, the drive ring 12 is also rotated clockwise from the initial position via the parent gear 11. At this time, the seven aperture blades 14 are rotated clockwise about the pin 14a by operating the pin 14b by the cam groove 12a. Therefore, the tip of each aperture blade 14 enters the opening 1a, and the aperture diameter (aperture aperture) formed by them is reduced.

On the other hand, the pin 13a of the light quantity limiting member 13
Due to the shape of the cam groove 12b, the drive ring 12 is not operated at the beginning of rotation, but is started to rotate later than the aperture blade 14. Therefore, while the diaphragm blades 14 are being rotated, the light amount limiting member 13 does not enter the opening changed by the blades 14. Then, when the predetermined aperture position is reached, the rotor 10 is stopped. Thereafter, when the opening / closing operation by the shutter blade is completed, the rotor 10 is rotated counterclockwise, and stopped when the drive ring 12 returns to the initial position, and the state shown in FIG. 1 is obtained.

FIG. 3 shows a state where the rotor 10 is stopped at the minimum opening position that can be formed by the seven diaphragm blades 14. In the case of the present embodiment, since the seven aperture blades 14 are stacked as described above, the aperture diameter cannot be further reduced. The reason for this is well known, because the tip of each diaphragm blade 14 hits another diaphragm blade and cannot rotate any further. However, even in such a case,
In the present embodiment, the presence of the light amount limiting member 13 enables shooting with a smaller aperture.

That is, in that case, the drive ring 12
It is further rotated clockwise from the state of FIG. At this time, the aperture blade 14 is not rotated by the shape of the cam groove 12a, but only the light amount limiting member 13 is rapidly rotated clockwise by the shape of the cam groove 12b, and stops in the state shown in FIG. . As is apparent from FIG. 4, the circular opening 13a formed in the light amount limiting member 13 has a smaller diameter than the minimum opening formed by the seven diaphragm blades 14. Moreover, since the opening 13a of the light quantity limiting member 13 is covered with the ND filter 13b, the light quantity of the subject is significantly reduced. And in this case, too,
When the opening / closing operation of the shutter blade is completed, the rotor 10 is rotated counterclockwise, and each member is returned to the state shown in FIG.

In this embodiment, the light amount limiting member 1 is used.
Although the ND filter 13b is affixed to 3, it is not always necessary to do so. In the case of this embodiment, the opening 1
The ND filter 13b is attached because it is desired to be able to limit the light amount more than the aperture of the size of 3a, and even so, if the aperture is further reduced, it will be affected by diffraction. I just do. Further, from this, the present invention provides the drive ring 12 with:
In addition to the cam groove 12b, another similar cam groove corresponding to the cam groove 12b is formed, and depending on the cam groove 12b, the light amount limiting member 13 to which the ND filter 13b is not attached is operated. Depending on the light amount limiting member 13
By operating the filter member of the shape according to
It is possible to perform both the light amount control by the opening 13a alone and the light amount control by the opening 13a and the filter member. And if you do that,
The filter member may have a configuration in which an ND filter is attached, or the filter member may be made of only the material of the ND filter.

In this embodiment, the aperture blade 14
Are arranged as described above, but when it is determined that there is no need to do so, each aperture blade 1
4 may be simply arranged in order. By doing so, it is theoretically possible to make the diameter of the minimum opening by the aperture blade 14 smaller than in the case of the present embodiment. However, as already described, there is no problem in obtaining an opening close to a circle from the viewpoint of manufacturing. Therefore, even when such an overlapping method is adopted, the minimum opening is set in this embodiment. Light amount limiting member 13 as in the example
It is best to regulate by.

Furthermore, in this embodiment, the fully opened state of the opening 1a has been described as the initial state. However, depending on the camera, the operation may be started with the state shown in FIG. 4 as the initial state. When the aperture blades 14 are simply overlapped in order as described above, the operation may be started with the opening 1a completely covered by the aperture blades 14 as an initial state.

[0028]

As described above, according to the present invention, a diaphragm mechanism for a camera in which a drive ring simultaneously rotates a plurality of diaphragm blades in the same direction to control a plurality of diaphragm apertures having different apertures. In the above, only the aperture stop having the minimum aperture can be obtained by the light amount limiting member having a circular opening, and the drive ring for operating the aperture blade also operates the light amount limiting member, so that a simple configuration is provided. Thus, a minimum aperture having an ideal shape can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment showing a state before photographing as viewed from a subject side.

FIG. 2 is a cross-sectional view mainly for easy understanding of the configuration of the motor in the embodiment.

FIG. 3 is a plan view of an embodiment showing a control state of a minimum aperture controllable by a plurality of diaphragm blades.

FIG. 4 is a plan view showing a state where a circular opening is inserted in the state of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ground plate 1a, 13a Opening 1b Depression 1c Hole 1d, 1e Hook 1f, 1g, 1h, 1i Base 1j, 1k, 13c, 14a, 14b Pin 1m Tube 1n, 1p, 1q Shaft 2 Cover plate 3 Screw 4 , 5 Yoke 4a, 4b, 5a, 5b Leg 4c, 5c Fitting section 6, 7 Coil 8, 9 Bobbin 10 Rotor 10a Permanent magnet 10b Gear 11 Parent-child gear 12 Drive ring 12a, 12b Cam groove 12c Tooth 13 Light intensity Limiting member 13b ND filter 14 aperture blade

Claims (5)

[Claims] 1. A plurality of diaphragm blades pivotally attached to a ground plate at equal angular positions around an optical axis and simultaneously rotating in the same direction to change a diaphragm aperture, and pivotally mounted to the ground plate. A light quantity limiting member capable of inserting a circular opening having a smaller diameter than the minimum aperture opening formed by the aperture blade into the optical path, and arranged so as to be rotatable about an optical axis; A drive ring connected to the light quantity limiting member in a fitting configuration with separate cam grooves and pins,
A cam groove used for connecting the drive ring and the aperture blade is such that when the drive ring inserts the opening of the light quantity limiting member into the optical path, the aperture blade is not substantially rotated. An aperture mechanism for a camera, wherein the aperture mechanism is formed in the camera. 2. The drive ring, wherein a cam groove used to connect the drive ring to the aperture blade and a cam groove used to connect the drive ring to the light amount limiting member are formed in the drive ring. The aperture stop mechanism for a camera according to claim 1, wherein: 3. An ND filter is attached to an opening of the light amount limiting member.
Aperture mechanism for a camera according to the above. 4. A driving ring, which is pivotally attached to the base plate, is connected to the driving ring by a fitting structure comprising a cam groove and a pin, and is provided only when the opening of the light quantity limiting member is inserted into an optical path. A filter member that allows an ND filter to be inserted into the optical path by a drive ring; a cam groove used to connect the drive ring to the aperture blade; and a cam groove used to connect the drive ring to the light amount limiting member. The cam groove is formed such that when the drive ring inserts the filter member into the optical path, the aperture blade and the light amount limiting member are not substantially rotated. 3. The aperture mechanism for a camera according to 2. 5. An aperture mechanism for a camera according to claim 1, wherein said drive ring is rotated by a motor.