JPH1068979A - Camera diaphragm mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera diaphragm mechanism which is at low cost by having shape memory alloy as a driving source and whose constitution is compact. SOLUTION: A diaphragm blade 2 having a small diaphragm diameter part 2a is rotatably attached at a bottom board 1 having an aperture part 1a. Though the diaphragm blade 2 is pressed in a counterclockwise direction by a spring 3, it is stopped by a stopper 1c. The bottom board 1 is made of synthetic resin, and a groove 1e is formed, and the guide part 1f of a circular-arc surface is formed at a corner part, a brattice part 1g is formed so as to cover it. Wire-like shape memory alloy 4 is arranged at the inside of the groove 1e, and one end is fixed at the bottom board 1 and the other end is fixed at the diaphragm blade 2. When voltage is applied to the shape memory alloy 4, the diaphragm blade 2 resists the spring 3 and is operated in a state shown by a chain line.

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, the aperture of which is controlled by using a shape memory alloy.

[0002]

2. Description of the Related Art In recent years, many aperture mechanisms for cameras have been configured to electrically operate aperture blades to a predetermined aperture position, and the driving sources thereof are mainly pulse motors and iris motors. It is used. And
These motors are arranged as close as possible to the lens with the axis of rotation of the rotor parallel to the optical axis. However, these motors have the disadvantage that they have a large number of parts and are relatively expensive. In addition, while the aperture blades can be arranged flat in the optical axis direction, the motor requires an excessively large dimension in the optical axis direction, making it impossible to configure the aperture mechanism as a whole flat. This places great constraints on the design of other configurations in the camera,
In recent years, it has become a major problem particularly for miniaturization of a camera, which has been increasingly required.

In order to solve such a problem, Japanese Patent Application Laid-Open No. Sho 61-146331 discloses a motor in which a wire-shaped shape memory alloy is used as a drive source instead of the above-described motor. I have. This diaphragm mechanism attaches two shape memory alloys with spring-shaped shape memory to a ring to which a plurality of diaphragm blades are attached, and when opening the diaphragm blades, one of the shape memory alloys is energized and deformed into a spring shape When the ring is rotated by the contraction action and the aperture blade is closed, the other shape memory alloy is energized to rotate the ring in the opposite direction. Therefore, this device has a feature that the installation volume is smaller than that using the above-described motor as a driving source, and the entire configuration can be particularly thinned in the optical axis direction.

[0004]

However, if two shape memory alloys are provided as described above, since the shape memory alloy itself is still expensive, the cost of the entire drawing mechanism increases, and At present, the shrinkage ratio of the shape memory alloy is not so large, so that if two are provided, the installation space is not so advantageous. Furthermore, the shape memory alloy shrinks relatively quickly when a voltage is applied, but it cannot be said that the shape memory alloy returns to its original state when the application of the voltage is stopped unless a cooling device is provided. Therefore, even if two shape memory alloys are attached so as to act in opposite directions as described above, the operating speed is limited by the other, and the effect of providing two shape memory alloys is expected. Can not. In addition, when one camera contracts, the other camera must have enough length so that the brake is not applied to the other camera. As a result, the stop position of the ring is not determined, and the diaphragm blade is placed in an extremely unstable state.

The present invention has been made to solve such a problem, and an object of the present invention is to make it thinner in the optical axis direction as in the above-mentioned conventional example and to have a comparable performance. However, an object of the present invention is to provide a camera aperture mechanism which is more advantageous in terms of space as compared with the conventional example and which is inexpensive.

[0006]

In order to achieve the above object, an aperture mechanism for a camera according to the present invention has a base plate having an opening concentric with an optical axis and at least one aperture aperture. A diaphragm blade rotatably attached to the main plate, a spring urging the diaphragm blade to rotate in one direction, a stopper for stopping rotation of the diaphragm blade by the urging force of the spring, and one end. A shape memory alloy, the other end of which is attached to the base plate and the contraction action causes the diaphragm blade to rotate in the other direction against the urging force of the spring; and And another stopper for stopping rotation.

According to another aspect of the present invention, there is provided a camera diaphragm mechanism comprising: a base plate having an opening concentric with an optical axis; and an operating member mounted on the base plate so as to be capable of reciprocating operation. A plurality of diaphragm blades, each of which is supported by the base plate and the operating member, regulates the opening to a small opening diameter by one of reciprocating operations of the operating member, and regulates the opening to a large opening diameter by the other operation. A spring for urging the operating member to operate in one of the reciprocating operations, a stopper for stopping operation of the operating member by the urging force of the spring, and one end connected to the operating member. A shape memory alloy that is attached to the base plate and operates the operating member against the urging force of the spring by a contraction action thereof, and stops the rotation of the operation member due to the contraction of the shape memory alloy. And a another stopper to.

In the aperture mechanism for a camera according to the present invention, preferably, the shape memory alloy is arranged in a groove formed in the base plate. Furthermore,
In these camera diaphragm mechanisms of the present invention, preferably, the voltage applying device of the shape memory alloy is provided with means for switching the applied voltage.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to a first embodiment shown in FIG. 1 and a second embodiment shown in FIGS. FIG. 1 is a plan view of the first embodiment, showing a state in which the opening of the exposure opening is maximized. 2 and 3 are plan views of the second embodiment, and FIG.
Shows a state in which the exposure opening is closed, and FIG. 3 shows a state in which the opening of the exposure opening is maximized. FIG. 4 is an explanatory diagram of a voltage application device for a shape memory alloy.

First, the configuration of the first embodiment will be described. The synthetic resin base plate 1 is formed at its center with a circular opening 1a concentrically arranged with the optical axis of the taking lens. An aperture blade 2 is rotatably mounted on a shaft 1b erected on the base plate 1, and an aperture 2a having a diameter smaller than the aperture 1a is formed therein. The aperture blade 2 is actually arranged in a blade chamber formed between the main plate 1 and the cover plate, but the cover plate is omitted in the drawing. The diaphragm blade 2 is urged by a spring 3 to rotate in a counterclockwise direction, and the rotation is stopped by a stopper 1c provided on the main plate 1. The clockwise rotation is stopped by the stopper 1d. Further, a groove 1e is formed in the base plate 1. A guide portion 1f having an arcuate surface is formed at a corner in the groove 1e, and an overhang portion 1g is formed on the front surface side of the drawing so as to cover the guide portion 1f. In the lower part of the groove 1e, at the place corresponding to the overhang 1g,
A hole 1h penetrating through the main plate 1 is formed, which is provided for forming.

A wire-shaped shape memory alloy 4 is disposed in the groove 1e, one end of which is mounted in the groove 1e, and the other end of which is mounted on the diaphragm blade 2. Each mounting method is the same, and each end is connected with a stopper 5,6.
And swage it, and use the stoppers 5, 6
Are fixed by screws 7 and 8. As is well known, this type of shape memory alloy has the property that its length shrinks when a voltage is applied across its ends and returns to its original state when cooled. Therefore, although not shown, lead wires are also connected to both ends of the shape memory alloy 4. In this case, the lead wires may be joined to the stoppers 5 and 6 by soldering, but it is convenient to caulk the stoppers together with the shape memory alloy 4 to the stoppers 5 and 6. When the shape memory alloy 4 is attached, fine adjustment of the length can be performed by changing the rotational positions of the stoppers 5 and 6.

Next, the operation of this embodiment will be described. FIG. 1 shows a state before photographing. The diaphragm blade 2 is rotated counterclockwise by a spring 3 and its stop position is a stopper 1.
c. At this time, the aperture blade 2
The base plate 1 is completely retracted from the opening 1a, and the opening 1a is in a fully opened state. When not in use, even if the shutter is fully opened in this manner, in a camera using a film, there is no problem if light leakage is prevented by a shutter or a special light-blocking member, and in a camera using a CCD element as a light receiving section. There is no problem because the power is turned off.

In photographing, when the power switch of the camera is closed, the aperture is first determined according to the photographing conditions. On the other hand, although not shown, in a camera equipped with an automatic focusing device, focusing is performed according to the subject distance. Is performed. As is well known, the aperture can be changed according to the brightness of the subject light, to change the depth of focus artificially, or to reduce the aperture for close-up shooting to ensure lens performance. Although it is known, in the present embodiment, in those cases, two apertures can be selected,
They can be selected manually or automatically. When the large aperture is selected, the aperture blade 2
Does not operate at all from the state of FIG. 1, and the aperture at that time is regulated by the opening 1a.

On the other hand, when a small aperture is selected, a predetermined voltage is applied to both ends of the shape memory alloy 4. As a result, the shape memory alloy 4 is heated and its length shrinks,
The aperture blade 2 is rotated clockwise against the force of the spring 3 and stopped by the stopper 1d. The state of the aperture blade 2 at that time is shown by a dashed line in FIG. 1, and the aperture at the time of photographing is regulated by the aperture aperture 2a. The photographing is performed after the aperture diameter is determined in this way, but when the photographing is performed with a small aperture, the application of the voltage to the shape memory alloy 4 is stopped when one photographing is completed. Therefore, the shape memory alloy 4 extends, so that the diaphragm blade 2
It is rotated counterclockwise by the urging force of the spring 3, and stops at the position indicated by the solid line in FIG.

As described above, according to the present embodiment, the small aperture setting position of the diaphragm blade 2 is regulated by the stopper 1d, so that the voltage value applied to the shape memory alloy 4 does not require much accuracy. In addition, since the shape memory alloy 4 and the stoppers 5 and 6 are arranged in the groove 1e, there is no need to consider interference with other members in operation. Further, in order to dispose the shape memory alloy 4 on the narrow ground plate surface, the shape memory alloy 4 must be bent. However, in this embodiment, since the arc-shaped guide portion 1f is formed at the corner, the friction is reduced. It can be minimized, and there is no fear that the shape memory alloy 4 will come off from the inside of the groove 1e by forming the overhang portion 1g.

In this embodiment, the diaphragm blade 2 is rotatably mounted on the main plate 1, but may be mounted so as to perform a reciprocating sliding movement. In the present embodiment, two calibers can be selected.
Two or more aperture diameter portions having different apertures may be formed on the aperture blade 2 so that two or more aperture diameters can be selected. However, in this case, since the diaphragm blades 2 must be stopped at three or more positions, there is a problem that the method of applying a voltage value becomes troublesome in setting an intermediate aperture. An example in which the diaphragm blade is stopped at three or more positions is shown in the second embodiment, and the description in that case will be left to the description of the second embodiment.

Next, a second embodiment of the present invention will be described with reference to FIGS. First, the configuration will be described with reference to FIGS. The base plate 11 and the cover plate 12 of the present embodiment are made of synthetic resin and have almost the same planar shape. The base plate 11 and the cover plate 12 are composed of three screws 13, 14, 15
And constitute a blade chamber between them. Openings 11 a and 12 a are formed in the base plate 11 and the cover plate 12 concentrically with the optical axis, respectively.
The aperture 1a has a smaller aperture than the aperture 12a, and regulates the maximum aperture of the diaphragm. Shafts 11b, 11 erected on the main plate 11 in the blade chamber
Although three diaphragm blades are rotatably attached to c and 11d, only the diaphragm blade 16 attached to the shaft 1b is shown for convenience. Further, a cam hole 16a is formed in the aperture blade 16 as is well known.

A cylindrical lens frame 11e is formed concentrically with the optical axis on the front side of the base plate 11, and a front lens frame of a photographic lens (not shown) is attached thereto. . Then, three projections 11f are radially formed on the lens frame 11e. Ground plate 1
A circular groove 11g is formed on the front side of the lens frame 11e along the outer periphery of the lens frame 11e.
1h. In the bottom of the groove 11g, three long holes 11i communicating with the blade chamber are formed.

In such a groove 11g, an aperture ring 1 is provided.
7 are rotatably mounted, and three pins 17a are inserted into the cam holes 16a of the respective aperture blades 16 by passing through the above-described elongated holes 11i. Further, three notch holes 17b are formed in the aperture ring 17, and when attaching the aperture ring 17, these notch holes 1b are formed.
7b is dropped into the groove 11g in alignment with the above-mentioned projection 11f, and is rotated by a predetermined angle before the aperture blade 16 is assembled. Further, the drawing ring 17 is provided with a spring 18 hung between the overhang 17 c and the main plate 11.
Urged to rotate clockwise.

A wire-shaped shape memory alloy 19 is attached to the projecting portion 17c at one end and to a shaft 11j erected on the base plate 11 at the other end by appropriate means. Of course, the mounting configuration described in the first embodiment may be used. And on both ends,
Lead wires (not shown) are connected. The rotation of the aperture ring 17 is stopped by the two stoppers 20 and 21 with which the overhang 17c abuts. These stoppers 20 and 21 are constituted by eccentric pins.
The stop position can be fine-tuned. When the aperture ring 17 rotates clockwise, the pin 17a
If it stops in contact with i, that is, the long hole 11i
The stopper 20 can be omitted if the end of the stopper 20 is used as a stopper. Needless to say, the stopper 21
After assembling the drawing ring 17, the depression 11
h.

Next, the operation of this embodiment will be described with reference to FIG. In addition, in the explanatory view of FIG. 4, reference numeral A denotes an aperture unit provided with the shape memory alloy 19 described above. Also,
Reference numeral B denotes a shape memory alloy driver, and reference numeral C denotes an applied voltage switching circuit. Reference numeral D denotes an aperture control circuit that activates the applied voltage switching circuit C and the driver B according to an input signal and outputs a signal indicating completion of setting the aperture.

FIG. 2 shows a state in which the camera is not used. In this state, the opening 11a is completely closed by three diaphragm blades 16 in order to reliably prevent light leakage. At the time of photographing, when the power switch is closed, a preset aperture value or an aperture value signal corresponding to the subject light is input to the aperture control circuit D. Thereby,
The aperture control circuit D first commands the applied voltage switching circuit C to switch to a resistance corresponding to the aperture value. Next, upon receiving the switching completion signal, the driver B is activated,
A voltage corresponding to the above aperture value is applied to the shape memory alloy 19.

The shape memory alloy 19 is heated when a voltage is applied, and contracts by an amount corresponding to the voltage value. Therefore, the aperture ring 17 rotates counterclockwise against the urging force of the spring 18 to open the aperture blade 16 and stops at a predetermined aperture position. When the stop of the aperture ring 17 is detected by a sensor (not shown), the aperture control circuit D outputs the detection signal, and the shutter open / close control circuit (not shown) is operated to perform photographing. Aperture control circuit D
Receives the photographing end signal, resets the applied voltage switching circuit C and stops the operation of the driver B. As a result, the voltage applied to the shape memory alloy 19 is cut off, and the length of the shape memory alloy 19 is extended, so that the aperture ring 17 is rotated clockwise by the urging force of the spring 18 to close the opening 12a. Then, the state returns to the state of FIG.
FIG. 3 shows a state in which the maximum aperture position, that is, the opening 11a is fully opened in such an operation of setting the aperture diameter.

As described above, according to the present embodiment, by changing the applied voltage, the aperture blade 16 can be stopped at a plurality of positions in addition to the fully open position. In addition, in order to perform such control, one terminal is connected to one end of the shape memory alloy, and a plurality of other terminals are provided at different length positions. There is also a method of selectively energizing, but in such a case, the configuration of the aperture unit becomes complicated, and it becomes difficult to smoothly perform a predetermined contraction operation. Therefore, it is mechanically simpler and more practical to configure and control as in this embodiment.

In this embodiment, the aperture blade 16 completely closes the opening 11a when the camera is not used. However, depending on the specification, the length of the long hole 11i may be shortened. By changing the position of the stopper 20, it is possible to set the minimum aperture position.
Also, by switching the directions of action of the spring 18 and the shape memory alloy 19 on the drawing ring 17, it is possible to bring the fully open state as in the first embodiment. Also,
In the present embodiment, the shape memory alloy 19 is
To avoid interference with other parts (not shown) as much as possible. However, in consideration of safety, it may be arranged in a narrow groove as in the first embodiment. When the wire 19 is extended long, a guide portion as in the first embodiment may be provided at the corner. Main plate 11
Is made of synthetic resin, the cost is not so high even with such a configuration. Further, in the present embodiment, the three diaphragm blades 16 are opened and closed by the reciprocating operation of the diaphragm ring 17, but in the present invention, the two diaphragm blades are relatively moved by the reciprocating operation of the lever. The present invention can also be applied to the above-described aperture mechanism.

[0026]

As described above, according to the present invention, since only one shape memory alloy needs to be prepared, a diaphragm mechanism for a camera which is more advantageous in terms of space and lower in cost than the conventional example described above is provided. In particular, if the base plate is made of a synthetic resin and a long shape memory alloy is accommodated in a concave portion such as a groove formed therein, the whole arrangement configuration becomes more advantageous.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is a plan view showing a second embodiment of the present invention, in which an exposure opening is closed.

FIG. 3 is a plan view showing a second embodiment of the present invention, and shows a state in which the opening of the exposure opening is maximized.

FIG. 4 is an explanatory view of a voltage applying device for a shape memory alloy according to a second embodiment of the present invention.

[Explanation of symbols]

 1,11 Ground plate 1a, 11a, 12a Opening 1b, 11b, 11c, 11d, 11j Shaft 1c, 1d, 20,21 Stopper 1e, 11g Groove 1f Guide 1g, 17c Overhang 1h Hole 2,16 Aperture blade 2a Diameter aperture 3,18 Spring 4,19 Shape memory alloy 5,6 Stopper 7,8,13,14,15 Screw 11e Lens frame 11f Projection 11h Depression 11i Slot 12 Cover plate 16a Cam hole 17 Aperture ring 17a Pin 17b Notch hole A Aperture unit B Driver C Applied voltage switching circuit D Aperture control circuit

Claims (4)

[Claims] A base plate having an opening concentric with the optical axis;
An aperture blade having at least one aperture diameter portion rotatably attached to the main plate, a spring urging the aperture blade to rotate in one direction, and the aperture blade by an urging force of the spring A stopper that stops the rotation of the shape memory alloy, one end of which is attached to the diaphragm blade and the other end is attached to the main plate, and the contraction action causes the diaphragm blade to rotate in the other direction against the urging force of the spring; An aperture mechanism for a camera, comprising: another stopper for stopping rotation of the aperture blade due to contraction of the shape memory alloy. 2. A base plate having an opening concentric with the optical axis;
An operating member attached to the main plate so as to be capable of reciprocating operation, each of which is supported by the main plate and the operating member and regulates the opening to a small opening diameter by one of the reciprocating operations of the operating member; A plurality of diaphragm blades for regulating to a large opening diameter by operation, a spring for urging the operation member to operate to one of the reciprocating operations, and an operation of the operation member by the urging force of the spring A shape memory alloy having one end attached to the actuating member and the other end attached to the base plate to actuate the actuating member against the urging force of the spring by a contracting action thereof; and a shrinkage of the shape memory alloy. A stop mechanism for stopping rotation of the operating member due to the above. 3. The aperture mechanism for a camera according to claim 1, wherein the shape memory alloy is disposed in a groove formed in the base plate. 4. A diaphragm mechanism for a camera according to claim 1, wherein said voltage applying device of said shape memory alloy is provided with means for switching an applied voltage.