JP2001337367A - Diaphragm switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm switching device capable of adjusting the exposure without using expensive parts and a large space. SOLUTION: This diaphragm switching device is equipped with a movable diaphragm plate 45 which is provided to freely move between a photographing lens 6 and a shutter blade 42 and where a 1st aperture 67 having a small diameter of opening and a 2nd aperture 66 having a large diameter of opening are formed and a fixed large diaphragm aperture 64a provided behind the plate 45. By moving the plate 45, the aperture 67 is used as the diaphragm of a photographing system when it is set on a photographing optical axis, and the aperture 64a is used as the diaphragm of the photographing system when the aperture 66 is set on the photographing optical axis. Then, the plate 45 is used as a flare stopper for intercepting harmful light made incident from the lens 6 and going toward the outside of a harmful exposure range on film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aperture switching device, and more particularly to an aperture switching device suitable for a simple camera such as a film unit with a lens.

[0002]

2. Description of the Related Art As a kind of a simple camera, various kinds of film units with lenses, in which a simple photographing mechanism such as a photographing lens and a shutter mechanism are incorporated, and a photo film is pre-loaded, are sold by the present applicant. Users can easily take print photos of good quality.
In this film unit with a lens, the F-number and shutter speed of the taking lens are fixed and the exposure conditions are always constant in order to reduce the cost and size. For this reason, the range of the shooting conditions in which the main subject such as a person and the background can be properly shot is narrow, and if the subject brightness is out of the range, the shooting image quality is deteriorated.

However, due to recent technical innovations, the film unit with a lens is also required to have higher functionality, and a mechanism for changing exposure conditions according to various photographing situations is being studied. JP-A-9-5817
In the publication, a movable diaphragm plate having an opening smaller in diameter than the fixed diaphragm opening, a photometric unit that measures the amount of light of the subject, and outputs a switching signal when the amount of light is equal to or more than a predetermined value, and at the time of outputting the switching signal An automatic exposure controller with an actuated electromagnet has been proposed. In this automatic exposure control device,
When the electromagnet operates, a magnetic attraction force is generated between the movable diaphragm plate and the electromagnet, and the diaphragm diameter can be switched by moving the movable diaphragm plate against the bias of the spring.

In order to prevent flare of subject light,
A flare stopper is provided on the front surface of the movable diaphragm plate. The movable diaphragm plate and the flare stopper have a light shielding property, and an inexpensive mylar film is used.

[0005]

However, when the operating environment changes from room temperature or low temperature to high temperature and high humidity, dew condensation occurs between the movable diaphragm plate and the flare stopper, and the friction increases. Further, when the use environment changes from high temperature and high humidity to normal temperature or low temperature, the movable diaphragm plate and the flare stopper may be stuck. Therefore, a large force is required to retract the movable diaphragm plate, and there is a disadvantage that a large electromagnet must be used. Therefore, the film unit with the lens provided with the automatic exposure control device requires a large space and increases the cost.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an aperture switching device capable of adjusting an exposure amount without using expensive components and a large space.

[0007]

In order to achieve the above object, an aperture switching device according to the present invention has a first aperture and a second aperture having different aperture diameters formed between a taking lens and shutter blades. A movable aperture plate is provided with a fixed open aperture behind the movable aperture plate, and the aperture of the imaging system is switched by one of the first aperture and the open aperture aperture by moving the movable aperture plate. When set on the optical axis of the taking lens, the movable aperture plate is used as a flare stopper for blocking harmful light entering from the taking lens and going out of the effective exposure range on the film. is there.

Further, the aperture switching device of the present invention is characterized in that the open aperture opening is formed in a lens base integrally formed with a lens barrel in which a taking lens is incorporated. The photographing lens includes a first lens and a second lens, and the movable diaphragm plate is provided between the first lens and the second lens.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, a film unit with a lens comprises a unit main body 2 and an exterior label 3 covering the surface of the unit main body 2. A photographing lens 6, a finder lens 7, a strobe light emitting unit 8, a strobe switching plate 9, and a light receiving element 10 are provided on the front of the unit body 2. 1
3 are provided. A part of the hoist knob 14 is exposed to the outside of the back at the back.

As shown in FIG. 3, the unit main body 2 includes a main body base 21, an exposure unit 22, and a strobe unit 2.
3, a cartridge body 24, a photographic film 25, and a front cover 4 and a rear cover 5 covering these.
The main body base 21 includes an exposure frame (not shown) for determining an exposure range of the photographic film 25, a cartridge storage chamber 27 for storing the cartridge main body 24, and a photo drawn out of the cartridge storage chamber 27 and wound into a roll. A photo film storage room 28 for storing the film 25 is provided. A winding knob 14 is attached to the upper part of the cartridge storage chamber 27, and the photographic film 25 is fed by rotating the winding knob 14.

The front cover 4 is provided on the front surface of the main body base 21, and has an opening for exposing the photographing lens 6, the finder 7, and the like to the outside. The rear cover 5 is provided behind the main body base 21 and covers the inside of the unit main body 2 together with the front cover 4 in a light-tight manner. Bottom cover 2 on rear cover 5
9a and 29b are integrally formed, and the cartridge body 24
And the bottom of the photo film 25 is light-tightly covered.

The strobe unit 23 includes the exposure unit 2
2, a printed circuit board 31 on which a strobe circuit is formed, a strobe light emitting section 8 attached to the printed circuit board 31, a capacitor 32, a battery 33, and a synchro switch 34. The strobe circuit is a circuit for charging the capacitor 32 with electric charge necessary for causing the strobe light emitting section 8 to emit light, and operates by depressing a push switch 35 provided on the printed circuit board 31.

The strobe switching plate 9 is provided so as to be slidable up and down to switch on / off the strobe circuit. When the strobe switching plate 9 is turned on, the push switch 35 is depressed, and the strobe circuit operates to charge the capacitor 32. Capacitor 32
When the charging of is completed, the flash charging confirmation window 13 flashes. Thereafter, when the synchro switch 34 is turned on, the strobe light is emitted from the strobe light emitting unit 8.

The exposure unit 22 is arranged on the front surface of the main body base 21. As shown in FIGS. 1 and 4, the exposure apparatus includes an exposure mechanism including a shutter blade 42, a shutter driving member 43, a connecting member 44, a lens base 64 for holding the photographing lens 6, and the like. An aperture switching mechanism including an electromagnet 46 is also provided.
A dark box 48 having a shutter opening 47 for guiding subject light into an exposure frame (not shown) is provided behind the exposure unit 22. A shutter lever 49 is provided above the exposure unit 22.
And a shutter mechanism for moving the shutter lever 49 held at the charge position to the release position.

The shutter blades 42 are provided so as to cover the shutter opening 47 in a normal state. Further, a bearing hole 42 a is provided in the shutter blade 42, and the shutter blade 42 is rotatably attached to a shaft provided on the front surface of the dark box 48.
Also, one end of the shutter blade 42 has a tip 42 b kicked off by the connecting member 44 and a synchro switch 34.
There is formed a flash emission projection 42c for turning on. A spring 53 is attached to the shutter blade 42, and the shutter blade 42 is held at a closed position that covers the optical axis by the bias of the spring 53. A synchro switch 34 is disposed beside the shutter blade 42. When the shutter blade 42 rotates to the open position, the projection 42d contacts the synchro switch 34, and the synchro switch 34 is turned on. The dark box 48 is provided with a stopper (not shown) so that the shutter blade 42 does not rotate counterclockwise from the closed position.

The shutter driving member 43 is provided beside the shutter blade 42 so as to be rotatable.
By the urging of 1, the distal end portion 43a is held at a position where it can be inserted into the movement area of the shutter lever 49. The shutter driving member 43 is provided with a projection 43b for locking the torsion spring 52 described later, a shaft 43c for attaching the connecting member 44, and a stopper 43d for restricting the movement of the connecting member 44.

The connecting member 44 is rotatable.
It is provided between the shutter blade 42 and the shutter driving member 43. A shaft 44a provided on the connecting member 44 includes:
A torsion spring 52 is attached. One end of the torsion spring 52 is connected to a protrusion 44 provided on the connecting member 44.
b, and the other end is a protrusion 43b of the shutter drive member 43.
Is engaged. The connecting member 44 is urged clockwise in the figure by the torsion spring 52, and the connecting member 44 is held in a state of contact with the stopper 44d. Further, the connecting member 44 is provided such that the tip end portion 44c abuts on the projection 42c of the shutter blade 42.

A lens base 64 disposed in front of the dark box 48 is provided with a fixed large stop aperture 64a and a lens barrel 64b. The lens base is mounted such that a fixed large aperture opening 64a is arranged in front of a shutter opening 47 provided in the dark box 48. The taking lens 6, the movable aperture plate 45, and the spacer 63 are housed inside the lens barrel 46b. Further, a groove 64c for positioning the spacer 63, a notch 64d for inserting the movable diaphragm plate 45, and a cylindrical surface of the lens barrel 64b are formed on the side surface of the lens barrel 64b of the lens base 64 from the front. An engagement projection 64e for attaching the lens holder 65 is provided.

The taking lens 6 inside the lens base 64 is
It comprises a first lens 61 and a second lens 62, between which a movable diaphragm plate 45 and a spacer 63 are arranged.
These are arranged in the order of the first lens 61, the movable diaphragm plate 45, the spacer 63, and the second lens 62 from the front in the order of the lens base 64.
Is housed inside. As the first lens 61, a meniscus lens having a convex surface on the object side is used, and as the second lens 62, a biconvex lens is used.

A lens holder 65 is mounted on the front surface of the lens base 64. Lens holder 65
Presses the outer peripheral portion of the first lens 61, and the photographing lens 6 is sandwiched and held between the lens base 64 and the lens holder 65.

The spacer 63 has an annular shape and is provided for adjusting the distance between the first lens 61 and the second lens 62. A positioning protrusion 63a is provided from the annular surface of the spacer 63, and is fitted into the groove 64c of the lens base 64. The spacer 63 is provided with a notch 63b on the front surface thereof so as to abut on the movable diaphragm plate 45 and also serves as a guide when the movable diaphragm plate 45 rotates.

The movable diaphragm plate 45 is formed in a thin plate shape, and is made of Mylar film.
Since Mylar film is inexpensive and has a light-shielding property, a low-cost aperture switching device can be manufactured. Mylar film is excellent in high strength, low shrinkage, thermal stability, chemical resistance and the like, and reliably fulfills the drawing function even in a bad environment.

The movable diaphragm plate 45 is disposed between the spacer 63 in the lens base 64 and the first lens 61. At one end of the movable diaphragm 45, two circular openings are provided in the up-down direction. Upper fixed aperture stop 64a
The second opening 66 has a larger opening diameter, and the lower side is a first opening 67 having a smaller opening diameter than the fixed large stop opening 64a.

The movable diaphragm plate 45 is rotatable about an opening 45a. A spring projection 45b is provided near the opening 45a, and one end of a spring 68 is hooked on the spring projection 45b. Then, the second opening 66 is held at the first position where it is inserted on the optical axis by the bias of the spring 68. At this time, the movable diaphragm plate 45 has a function of a flare stopper for preventing flare, and blocks stray light of subject light. Also, the movable diaphragm plate 45 does not fulfill the function as a diaphragm, and only the fixed large diaphragm aperture 64a plays the role of the diaphragm. Usually, the movable diaphragm plate 45 is arranged at the first position. Then, by rotating the movable stop clockwise in the figure, the first opening 67 becomes the second position where it is inserted on the optical axis. At this time, the movable diaphragm plate 45, together with the fixed large diaphragm aperture 64a, not only blocks stray light but also fulfills the function of a diaphragm for adjusting the exposure amount.

The electromagnet 46 is mounted between the dark box 48 and the photo film storage room 28 and is connected to a photometric circuit 70. The photometric circuit 70 is formed on the printed circuit board 31 (see FIG. 3) together with the light receiving element 10, and a photometric switch 71 for operating the photometric circuit 70 is arranged beside the shutter driving member 43. When the shutter driving member 43 rotates, the contact piece of the photometric switch 71 is pushed down, the photometric switch is turned on, and the photometric circuit 70 operates.

The light receiving element 10 measures the brightness of the subject, and the photometric circuit 70 energizes the electromagnet 46 when detecting that the brightness of the subject is equal to or higher than the reference value. An iron piece 72 is attached to one end of the movable diaphragm plate 45, and when the electromagnet 46 is energized, an attractive force is generated between the electromagnet 46 and the iron piece 72. Then, the movable aperture plate 45 is moved to the first opening 67.
Moves to the second position where it is inserted on the optical axis, and the electromagnet 4
6 comes into contact with the iron piece 72, and the movable diaphragm plate 45 stops at this position.

Next, the operation of the above configuration will be described. The photographer turns the winding knob 14 to set the unexposed photographic film 25 inside an exposure frame (not shown). With the rotation of the hoisting knob 14, the shutter lever 49 is charged. When the photographic film 25 is wound up by exactly one frame, the film winding stopping mechanism is operated, and the rotation of the winding knob 14 is locked.

When the shutter is charged, the shutter lever 49 is moved to the shutter driving member 4 as shown in FIG.
3 is held at the charge position on the left side in the figure.
The shutter driving member 43 is held by the bias of the spring 51, and the connecting member 44 is connected to the torsion spring 52.
As a result, it is held at a position where it comes into contact with the stopper 43d.

When the photographer performs framing of the subject and then depresses the shutter button 11, the shutter driving member 43 is kicked off by the shutter lever 49, and the shutter driving member 43 rotates (forwards) in the clockwise direction in the figure. At this time, since the torsion spring 52 is charged, the connecting member 44 also rotates integrally with the shutter driving member 43. Then, the front end portion 44c is connected to the shutter blade 42.
The shutter blade 42 is rotated in the counterclockwise direction in FIG.
Cannot rotate counterclockwise in the figure when in the closed position. For this reason, the connecting member 44 is
4c rotates counterclockwise in the figure around the shaft 43c while keeping the tip 4b of the shutter blade 42 in contact with the tip 42b.
When the shutter driving member 43 rotates, the photometric switch 71 is turned on, and the photometric circuit 70 operates to perform photometry of the subject.

When the shutter driving member 43 further rotates, the distal end portion 44c of the connecting member 44 is disengaged from the distal end portion 42b of the shutter blade 42, and the connecting member 44 is biased by the torsion spring 52 in the clockwise direction in FIG. To rotate.
Then, as shown in FIG. 5, the connecting member 44 is held in a state of being in contact with the stopper 43d.

When the shutter driving member 43 rotates by a predetermined amount, the bias of the spring 51 becomes strong, so that the rotation of the shutter driving member 43 stops, and thereafter, as shown in FIG. Rotate (return) clockwise. Since the connecting member 44 is held by the stopper 43d, the connecting member 44 moves back together with the shutter driving member 43. During this backward movement, the distal end portion 44c of the connecting member 44 kicks off the distal end portion 42b of the shutter blade 42, so that the shutter blade 42 rotates clockwise in the drawing.

While the connecting member 44 is moving forward, the shutter blades 42 are not kicked off.
By the time the exposure starts, a time lag occurs due to the forward movement of the connecting member 44. By adjusting this time lag to be the time required for switching the aperture, the aperture can be switched reliably. After the exposure, exposure can be performed.

When the subject is dark, the movable diaphragm plate 45 is held at the first position. As shown in FIG.
The subject light passes through the first lens 61, the second opening 66, the second lens 62, and the fixed large aperture opening 64a, and is exposed to the film 73. At this time, the exposure range 7 defined by the exposure frame 74 is determined only by the fixed large aperture opening 64a serving as an aperture.
5 Insufficient to block out harmful light going out, causing flare. Therefore, by arranging the second opening 66 in front of the fixed large stop opening 64a, harmful light traveling outside the exposure range 75 is prevented from reaching the film 73 directly or by reflection, thereby suppressing the occurrence of flare.

On the other hand, when the subject is bright, the electromagnet 4
6 to generate an attractive force between the electromagnet 46 and the iron piece 72, thereby rotating the movable diaphragm plate 45 to the second position. As a result, as shown in FIG. 7B, the subject light passes through the first lens 61, the first aperture 67, and the second lens 6.
2. The film 73 passes through the fixed large aperture opening 64a and is exposed to the film 73. At that time, the first opening 67 and the fixed large stop opening 64a prevent the harmful light going outside the exposure range 75 defined by the exposure frame 74 from reaching the film 73 directly or by reflection, thereby preventing the occurrence of flare. suppress. In addition,
Since the exposure amount is reduced to an appropriate value by the first opening 67 having a smaller diameter than the fixed large-aperture opening 64a, it is possible to perform photographing appropriately.

In the above embodiment, the movable diaphragm plate is rotated by passing an electric current through the electromagnet. However, as shown in FIG. 8, a film unit with a lens in which the user can manually switch the diaphragm can be implemented. is there. The exposure unit is a dark box 86, shutter blade 87, lens base 8
8 and the like. At the center of the dark box 86, a shutter opening 89 is formed, and the shutter blade 87 is covered. The shutter blade 87 is a known one that rotates clockwise against the bias of the spring 90 when the shutter is released. A fixed stop aperture 91 is formed in the lens base 88.
A lens barrel 92 is provided integrally with the lens base 88 around the fixed stop aperture 91. Inside the lens barrel 92, a photographing lens 83 including a first lens 93 and a second lens 94, and a spacer 95 are arranged.
6 housed together.

Between the first lens 93 and the spacer 95, an aperture changeover switch 85 exposed outside the lens-fitted film unit, a first aperture 97 having an aperture diameter smaller than the fixed aperture aperture 91, and a fixed aperture aperture. A movable aperture plate 99 is integrally formed with a second opening 98 having an opening diameter larger than 91. A slide groove 92a is formed on a side portion of the lens barrel 92, and a concave portion 95a is formed on a front surface of the spacer 95, and the movable diaphragm plate 99 is slidable left and right.

When the movable diaphragm plate 99 is at the first position, the first opening 97 is inserted on the optical axis. On the other hand, when the movable diaphragm plate 99 is at the second position, the first opening 97 retreats from the optical axis, and the second opening 98 moves on the optical axis. The movable diaphragm plate 99 is held at either the first position or the second position by a click stop. Thereby, the friction when moving the movable diaphragm plate can be minimized, and the diaphragm can be reliably switched without using expensive components and a large space.

In the above embodiment, the number of constituent lenses of the photographing lens 6 is not limited to two, but may be one or three or more. When the movable aperture plates 45 and 99 are used as flare stoppers, the second apertures 66 and 98 each having an opening diameter larger than the fixed aperture aperture are set on the photographing optical axis. When the configuration of the taking lens 6 is different, such as when the lens disposed on the front surface of the lens has a negative power, the second aperture may be smaller in diameter than the fixed aperture aperture, and the first aperture formed on the movable aperture plate may also The diameter of the second opening is not always larger than the diameter of the first opening. Further, in the present invention, the position of the movable diaphragm plate is set between the first lens and the second lens. However, it is effective to change the position to another position such as the rear surface of the second lens. Further, the present invention is effective even if the large aperture is not integrated with the shutter base.

[0039]

As described above, according to the aperture switching device of the present invention, since the movable aperture plate in which the first opening and the second aperture are formed integrally is used, friction is required to rotate the movable aperture plate. And the movable diaphragm plate can be rotated with a small force. Therefore, it is possible to reliably switch the aperture without using expensive components and a large space. Further, the movable diaphragm plate not only plays a role of a diaphragm but also plays a role of a flare stopper, so that there is no fear of flare.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a main part of an aperture switching device embodying the present invention.

FIG. 2 is an external view of a film unit with a lens embodying the present invention.

FIG. 3 is an exploded perspective view of the film unit with a lens shown in FIG. 2;

FIG. 4 is an explanatory diagram of an aperture switching device embodying the present invention.

FIG. 5 is an explanatory diagram of an aperture switching device embodying the present invention.

FIG. 6 is an explanatory diagram of an aperture switching device embodying the present invention.

FIG. 7 is an explanatory diagram of an aperture switching device embodying the present invention.

FIG. 8 is a schematic perspective view of a main part of an aperture switching device embodying the present invention.

[Explanation of symbols]

 Reference Signs List 6 photographing lens 10 light receiving element 22 exposure unit 42 shutter blade 45 movable diaphragm plate 46 electromagnet 47 shutter opening 63 spacer 64 lens base 66 second opening 67 first opening 72 iron piece

Claims (3)

[Claims] 1. A movable diaphragm plate movably provided between a taking lens and a shutter blade and having a first opening having a small opening diameter and a second opening having a large opening diameter, With a fixed open aperture opening provided behind,
When the first aperture is set on the photographing optical axis by the movement of the movable diaphragm plate, the first aperture is used as a diaphragm of the photographing system,
When the second aperture is set on the photographing optical axis, the open aperture is used as a diaphragm of the photographing system, and the movable diaphragm plate blocks harmful light that enters from the photographing lens and goes out of the harmful exposure range on the film. An aperture switching device characterized in that it is used as a flare stopper. 2. An aperture switching device according to claim 1, wherein said open aperture aperture is formed in a lens base integrally formed with a lens barrel in which a taking lens is incorporated. 3. The photographing lens includes a first lens and a second lens, and the movable diaphragm plate is provided between the first lens and the second lens.
An aperture switching device according to any one of the preceding claims.