JPH10123583A - Camera shutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera shutter where a shape memory alloy is taken as a driving source so as to set the shutter device and which is most preferable to be miniaturized and motor-driven. SOLUTION: When an voltage is separately applied to both ends of wire- shaped shape memory alloys 10 and 11, the alloys become shorter in length, then, a 1st blade driving member 2 and a 2nd blade driving member 3 are moved to a set position. And, the working pins 2a and 3a of the member 2 and 3 are locked by hook parts 20a and 21a of a 1st blade locking member 20 and a 2nd blade locking member 21 so as to maintain the set state. At photographing, the voltage is applied to both ends of the shape memory alloys 24 and 25 at a stage where iron piece members 4 and 5 are attracted and held by electromagnets 36 and 37, then, respective locking members 20 and 21 are released from locking, and then, it is allowed to perform the exposure operation by respective driving members 2 and 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shutter provided with a motorized device suitable for downsizing a camera.

[0002]

2. Description of the Related Art Recently, demands for downsizing and motorization of cameras have been further increased, and various proposals have been made and implemented in order to meet the demands. Among them, regarding motorization, the film winding operation has been automatically performed by a motor, and the lens has also been moved by a motor to automatically perform focus adjustment. Further, the shutter device has been electrified, and the setting operation has been generally performed by the same motor in conjunction with the film winding operation described above. Also, as for the release operation of the shutter device, there has been practiced one in which, after a release button of a camera is pressed, an electromagnet or a plunger is operated in response to a signal indicating that automatic focusing has been completed.

[0003] The shutter device includes a focal plane shutter and a lens shutter. In general, the focal plane shutter is such that, when an exposure operation is performed, a front blade opens an exposure opening and a rear blade closes the exposure opening. However, some lens shutters include a front blade and a rear blade that function similarly. When the shutter device including the front blade and the rear blade is set electrically as described above, a set member relating to both the front blade drive member and the rear blade drive member is provided, and the set member is provided. Normally, each of the above-mentioned driving members is operated to the set position by operating from the initial position to the set position in conjunction with the winding of the film.

[0004]

However, as described above, there is an extremely strong demand for miniaturization, and in particular, IX2
The emergence of the 40 cartridge film (Advanced Photo System Film) has further spurred it. In this case, the key point is how to reduce the size of the above-mentioned electric device to improve the space efficiency. However, there is a problem that the cost is rather high when trying to make it. As a mechanical component, a mechanism for interlocking with a film winding motor is required when setting the shutter device. Therefore, not only is there a problem in space but also a restriction on the arrangement relationship of the shutter device in the camera. There is a problem of receiving it. Further, since the above-mentioned setting member needs to set both the driving member for the front blade and the driving member for the rear blade, the arrangement in the shutter device is determined by itself and is a relatively large part. However, this has been a bottleneck in downsizing.

The present invention has been made to solve such a problem, and an object of the present invention is to use a shape memory alloy as a drive source without using the above-mentioned electromagnetic components and set members. An object of the present invention is to provide a camera shutter which is optimal for miniaturization and motorization in which a shutter device is set.

[0006]

In order to achieve the above object, a camera shutter according to the present invention comprises a base plate having an opening for exposure, a driving spring for reciprocating operation, and a driving spring for leading blades at the time of exposure operation. A driving member for the front blade which is operated from the set position to open the exposure opening to the front blade, and when a voltage is applied, the driving member for the front blade is moved to the set position against the driving spring for the front blade. Actuating first
A shape memory alloy, a front blade locking member for locking the front blade driving member at the set position, and a suction of the front blade driving member at the set position before releasing the locking of the front blade locking member. An electromagnet for the front blade that releases the holding force in response to a signal from the exposure time control circuit after holding and releasing the lock, and a reciprocating operation that can be performed from the set position by the driving spring for the rear blade during the exposure operation. A rear blade drive member for closing the exposure opening to the blade, and a second shape memory alloy for operating the rear blade drive member to a set position against the rear blade drive spring when a voltage is applied. A locking member for the rear blade that locks the driving member for the rear blade at the set position; and a suction and holding mechanism for the driving member for the rear blade at the set position before the locking of the locking member for the rear blade is released. Signal from the exposure time control circuit after Flip and and a blade electromagnet after releasing the holding force.

Further, in the camera shutter according to the present invention, preferably, a voltage is applied to the second shape memory alloy a predetermined time after a voltage is applied to the first shape memory alloy. In the camera shutter of the present invention, preferably, at least one of the first shape memory alloy and the second shape memory alloy has one end attached to the base plate and the other end connected to one of the drive members. So that it is attached to the Alternatively, at least one of the first shape memory alloy and the second shape memory alloy has both ends attached to the base plate, and the both ends are hung on one of the driving members.

Further, in the camera shutter according to the present invention, preferably, the third shape memory alloy for operating the front blade locking member to release the locking of the front blade driving member when a voltage is applied. And a fourth shape memory alloy that, when a voltage is applied, activates the locking member for the rear blade and releases the locking of the driving member for the rear blade.
In that case, preferably, at least one of the third shape memory alloy and the fourth shape memory alloy has one end attached to the base plate and the other end attached to one of the locking members. I do. Or, at least one of the third shape memory alloy and the fourth shape memory alloy,
Both ends are attached to the base plate, and the both ends are hung on one side of the locking member.

Still further, in the camera shutter according to the present invention, preferably, the third shape memory alloy and the fourth shape memory alloy are used.
Instead of a shape memory alloy, a shape memory alloy having both ends attached to the front blade locking member and the rear blade locking member, respectively, and having both ends attached to the base plate, When the voltage is applied to the first blade, the locking member for the front blade and the locking member for the rear blade are simultaneously operated to release the locking between the driving member for the front blade and the driving member for the rear blade. Still further, in the camera shutter of the present invention, preferably, instead of the third shape memory alloy and the fourth shape memory alloy, both ends are attached to the base plate, respectively, and two places between the both ends are attached to the front end. A locking member for the blade and a shape memory alloy hung on the locking member for the rear blade, wherein when a voltage is applied to the shape memory alloy, the locking member for the front blade and the locking member for the rear blade are separated. They are operated substantially simultaneously to release the locking of the front blade drive member and the rear blade drive member.

[0010]

1 to 3 show an embodiment of the present invention.
An example will be described with reference to FIG. Further, two modified examples of a part of the configuration shown in the embodiment will be described with reference to FIGS. FIG. 1 is a plan view showing a state immediately before the end of shooting in the embodiment before setting, and FIG. 2 is a plan view showing a state after setting. FIG. 3 is a timing chart for explaining the operation of the embodiment. FIGS. 4 and 5 are partial side views for explaining a part of the modification of the embodiment.

First, the configuration of the embodiment will be described. In this embodiment, the present invention is applied to a focal plane shutter. As is well known, the shutter base plate 1 made of synthetic resin is formed with an exposure opening 1a at a substantially central portion, but only the left part thereof is shown in the drawing.
On the back side of the shutter base plate 1, an intermediate plate and a cover plate (not shown) are sequentially attached at a predetermined interval, as is well known. An opening having a shape similar to that of the opening 1a is also formed in the intermediate plate and the cover plate, and an exposure opening as a shutter device is determined by combining these three openings. In the case of the present embodiment, the leading blade is arranged between the shutter base plate 1 and the intermediate plate, and the trailing blade is arranged between the intermediate plate and the cover plate.

On the front side of the shutter base plate 1, a shaft 1
b, 1c, 1d, 1e, 1f, 1g are erected,
Of these, the shafts 1b and 1c also protrude to the rear side of the shutter base plate 1, and the portions are formed thin. Although not shown because it is well known, the front blade and the rear blade in the present embodiment each have a configuration in which a plurality of divided blades are pivotally supported on two arms pivotally mounted on the rear side of the shutter base plate 1. Each of the arms (hereinafter referred to as the main arm)
It is pivotally connected to the shaft 1b and the shaft 1c. The shutter base plate 1 is formed with arc-shaped holes 1h and 1i penetrating therethrough.

On the front side of the shutter base plate 1, the shaft 1
A driving member 2 for the front blade and a driving member 3 for the rear blade made of synthetic resin are rotatably attached to b and 1c. These driving members 2 and 3 have operating pins 2a and 3a, respectively.
Mounting portions 2b and 3b are provided. The operating pins 2a and 3a penetrate the arc-shaped holes 1h and 1i, and are fitted into holes formed in the main arms of the front blade and the rear blade. Therefore, when the leading blade driving member 2 rotates in the counterclockwise direction, the operating pin 2a operates the main arm in the counterclockwise direction to deploy the divided blades, and when rotated in the clockwise direction, the operating pin 2a The main arm is operated clockwise so that the divided blades overlap. On the other hand,
When the rear blade drive member 3 rotates counterclockwise,
The operating pin 3a operates the main arm in the counterclockwise direction to overlap the divided blades, and when the operating pin 3a operates the main arm in the clockwise direction, the split blades are deployed.

Also, the mounting portions 2b, 3 of the driving members 2, 3
b is formed so as to protrude to the near side in FIG. 1, and the iron piece members 4 and 5 are attached thereto, respectively.
In order to clarify the specific mounting configuration, the portion is shown in cross section in FIGS. The iron piece members 4 and 5 are composed of iron pieces 4a and 5a to be attracted to an electromagnet, shafts 4b and 5b loosely fitted into holes formed in the mounting portions 2b and 3b, and a flange 4c. 5c, and can move in the axial direction of the shaft portions 4b and 5b. Then, the iron pieces 4a, 5a and the mounting portion 2
Compression springs 6 and 7 are interposed between b and 3b, and urge the flanges 4c and 5c to come into contact with the mounting portions 2b and 3b. The front blade drive member 2 and the rear blade drive member 3 are urged to rotate clockwise by a front blade drive spring 8 and a rear blade drive spring 9, respectively. , 9 are connected to the mounting portions 2b, 3 described above.
The other end is hung on spring hooks 1j and 1k provided on the shutter base plate 1.

Further, wire-shaped shape memory alloys 10 and 11 are respectively attached to the front blade driving member 2 and the rear blade driving member 3.
Are attached to the shutter base plate 1, and the other ends thereof are attached to the shutter base plate 1. Each mounting method is the same, with each end at the stop 12, 13, and 14,
15 and crimped, and the fasteners 12, 13, 14, 15 are screwed to the screws 16, 17, 18, 1
9 for fixing. These shape memory alloys 10,
11 has the property that its length contracts when a voltage is applied to both ends thereof, and returns to its original state when cooled. Therefore, although not shown, in the present embodiment, the lead wires are formed together with the shape memory alloys 10 and 11 together with the stoppers 12, 13, 14, and 14.
It is crimped to 15. And shape memory alloy 1
The expansion and contraction of 0 is performed using the column 1m and the spring hook 1j provided on the shutter base plate 1 as a guide, and the expansion and contraction of the shape memory alloy 11 is performed using the columns 1n and 1p provided on the shutter base plate 1. Needless to say, a predetermined space is provided between the pillar 1n so that the tip of the pillar 1n does not contact the rear blade drive member 3.

A locking member 20 for the front blade and a locking member 21 for the rear blade are rotatably mounted on the shafts 1d and 1e of the shutter base plate 1, respectively. The locking members 20, 21
Having hook portions 20a, 21a and springs 22, 23;
Is biased to rotate clockwise by
These rotations are stopped by stoppers 1q and 1r provided on the shutter base plate 1. One ends of wire-shaped shape memory alloys 24 and 25 are attached to these locking members 20 and 21, respectively, and the other ends thereof are attached to the shutter base plate 1. However,
One ends of the shape memory alloys 24 and 25 are respectively connected to stoppers 26 and
The other end thereof is caulked by a screw 27 and fixed by screws 28 and 29, and the other end thereof is fixed by a common stopper 30 and fixed by a screw 31. In addition, the properties of these shape memory alloys 24 and 25 are the same as those of shape memory alloy 1
The expansion and contraction are performed using the columns 1s, 1t, and 1u provided on the shutter base plate 1 as guides. It should be noted that, when the leads crimped to the stopper 30 are connected to the plus, the respective leads crimped to the stoppers 26 and 27 are connected to the minus.

Further, tensioners 32 and 33 are rotatably mounted on the shafts 1f and 1g of the shutter base plate 1, respectively. These tensioners 32 and 33 are urged clockwise and counterclockwise by springs 34 and 35, respectively, and their pins 32a and 33a always contact the shape memory alloys 10 and 11, respectively. 10,1
1 is kept in tension.

Although not shown because it is well known, a mounting plate (sometimes referred to as an upper base plate) is mounted on the front side of the shutter base plate 1 so as to be parallel to the shutter base plate 1. I have. An electromagnet 36 for the front blade and an electromagnet 37 for the rear blade are attached to the lower surface, that is, the surface on the shutter base plate 1 side. Therefore, FIGS. 1 and 2
, The electromagnets 36 and 37 are indicated by alternate long and short dash lines. The electromagnets 36 and 37 in the present embodiment are
6a and 37a are U-shaped so that the iron pieces 4 and 5 are attracted by the two magnetic pole portions, respectively, and have a configuration in which coils 36b and 37b are wound around one magnetic pole portion, respectively. . However, since the two magnetic pole portions of the iron core members 36a and 37a are arranged so as to be perpendicular to the shutter base plate 1, only one of the magnetic pole portions is visible in the drawing.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 1 shows a state immediately after the end of shooting. Therefore, the front blade drive member 2 and the rear blade drive member 3
Means that the exposure operation has been completed by the respective drive springs 8 and 9, and the photographer is still holding down the release button of the camera. In this state, the divided blades of the leading blade (not shown) overlap with each other to expose the opening 1a for exposure.
The split blades of the rear blade are spread out and cover the exposure opening 1a.

In this state, when the pressing force of the release button is released, the power switch SW is turned off. Even if the power switch SW is turned off, the film winding motor Mo and the shape memory are kept for a predetermined time. Alloys 10, 11
(In FIG. 3, reference numerals SMA1 and SMA2) can be supplied with electric power. Then, when the motor Mo is operated by the off signal of the power switch SW and the winding of the film is started, at the same time, the shape memory alloy 10 (SMA)
A voltage is applied to 1). for that reason,
The shape memory alloy 10 contracts rapidly and becomes short, and rotates the leading blade drive member 2 counterclockwise against the leading blade drive spring 8. By this rotation, the driving member 2 for the leading blade
Rotates the main arm of the leading blade (not shown) counterclockwise about the shaft 1b by the operating pin 2a. As a result, the split blades (not shown) start operating upward while being deployed.

Immediately before the set position, the operation pin 2a is moved to a hook portion 20a formed on the front blade locking member 20.
Is pressed, and the front blade locking member 20 is rotated counterclockwise against the spring 22 by the cam action. At this time, since the shape memory alloy 24 is slightly loosened, it is actually necessary to prevent the shape memory alloy 24 from coming off the column 1s. As an example, it is convenient to make the column 1s thicker, form a through hole in the side of the column, and let the shape memory alloy 24 pass through the hole. In this way, the operating pin 2a pushes the locking member 20 for the leading blade, and when the pushing relation is released soon, the locking member 20 for the leading blade performs a returning operation in the clockwise direction by the spring 22. As shown in FIG. 2, the hook portion 20a enters into the operation locus of the operation pin 2a. As can be seen from this, the operation of the front blade locking member 20 by the spring 22 is also restricted by the length of the shape memory alloy 24, so the stopper 1q is not necessarily required.

Thus, the shape memory alloy 10 (SM
Even if the power supply to A1) is cut off, the leading blade driving member 2
Will be maintained in the set state. And
In the set state, the compression spring 6 is compressed, and the iron piece 4a of the iron piece member 4 is in contact with the iron core member 36a. On the other hand, when the current is cut off, the shape memory alloy 1
0 is elongated, but the tensioner 32 is rotated clockwise by the spring 34 with the extension, and the shape memory alloy 10 is always in a tension state as shown in FIG. It does not deviate from 1 m or the spring hook 1j and does not affect the operation of itself or other members by loosening. In order to allow the shutter to be loosened without providing the tensioner 32, a groove may be formed on the surface of the shutter base plate 1, and the shape memory alloy 10 may be disposed in the groove. However, in such a case, it is necessary to take measures to prevent the shape memory alloy 10 from protruding from the groove when loosened. It should be noted that other shape memory alloys according to the present embodiment may be arranged in the grooves as described above.

Now, as described above, the shape memory alloy 10 (S
At the same time as the energization of MA1) is stopped, a voltage is applied to shape memory alloy 11 (SMA2). for that reason,
The shape memory alloy 11 becomes shorter, and rotates the rear blade drive member 3 counterclockwise against the rear blade drive spring 9. By this rotation, the driving member 3 for the rear blade is moved to the operating pin 3a.
The main arm of the rear blade (not shown) is
To rotate counterclockwise, and operate upward while overlapping the divided blades (not shown). The subsequent operation of the rear blade driving member 3 is substantially the same as the setting operation of the front blade driving member 2 described above, and the operating pin 3a temporarily pushes the rear blade locking member 21 counterclockwise. Thereafter, the rear blade locking member 21 is returned by the spring 23 to be locked at the set position. Then, in that state, the compression spring 7
Is compressed, and the iron piece portion 5a of the iron piece member 5 is
Contact.

Thereafter, when the energization of the shape memory alloy 11 (SMA2) is cut off, the shape memory alloy 11 expands, but also in this case, the tensioner 33 rotates counterclockwise, causing the shape memory alloy 11 to be in a tensioned state. Will be kept. In this way, all the members are in the set state shown in FIG. 2, but at that time, the film winding motor Mo
Is stopped, and the film winding is completed. In the above description, the setting operation of the rear blade drive member 3 is started after the setting of the front blade drive member 2 is completed, but the shape memory alloy 10 (S
If there is no influence on the supply voltage to MA1), like the well-known focal plane shutter, the driving member 2 for the leading blade
It is preferable to start the operation of the rear blade drive member 3 after a predetermined time has elapsed and before the set operation has been completed yet.

Next, the release operation will be described. When the release button of the camera is pressed, the power switch SW is closed at the initial stage, the photometering circuit and the distance measuring circuit work, and both the coils 36 of the electromagnet 36 for the front blade and the electromagnet 37 for the rear blade.
b, 37b are energized, and the iron core members 36a, 37a are excited. Therefore, the iron piece portions 4a,
5a is magnetically attracted and held by the iron core members 36a and 37a. When the holding force is sufficiently obtained, the two shape memory alloys 24 and 25 (SMA3 and SMA in FIG. 3) are obtained.
4) is energized. Therefore, each of the shape memory alloys 24, 25
And the locking members 20 and 21 are rotated counterclockwise to release the locking of the driving members 2 and 3.

At this stage, the photographer can confirm the suitability of the photographing conditions and the like using a known display device. If the photographer wants to stop shooting, the release of the release button is released, and first, the shape memory alloys 24 and 25 are released.
Is stopped, the locking members 20 and 21 return to the locking positions of the driving members 2 and 3, and then the coils 36b and 3
7b will be cut off. On the other hand, if it is determined that shooting is to be performed at this stage, the release button is further pressed. Then, the lens extension operation is performed based on the distance measurement result, and the exposure time control circuit operates in conjunction with the operation stop signal.

First, the exposure time control circuit cuts off the current to the coil 36b of the electromagnet 36 for the leading blade. As a result, the leading blade drive member 2 rotates clockwise by the force of the leading blade drive spring 8, and operates the main arm of the leading blade clockwise by the operating pin 2a. Therefore, the plurality of divided blades constituting the leading blade are superimposed and open the exposure opening 1a. On the other hand, in this process, since the leading blade drive member 2 pulls the shape memory alloy 10,
The tensioner 32 is rotated counterclockwise against the urging force of the spring 34. Immediately after the first blade has opened the exposure opening 1a, the operating pin 2a collides with the lower edge of the hole 1h, and stops after being prevented from bouncing by means not shown.

After a predetermined time corresponding to the photometry result after the energization of the coil 36a of the electromagnet 36 for the front blade is cut off, the energization of the coil 37b of the electromagnet 37 for the rear blade is cut off. Therefore, the biasing force of the rear blade drive spring 9 rotates the rear blade drive member 3 clockwise, and the operating pin 3a operates the main arm of the rear blade clockwise.
As a result, the plurality of divided blades constituting the rear blade group are developed and close the exposure opening 1a. In the meantime, since the rear blade drive member 3 pulls the shape memory alloy 11, the tensioner 33 is rotated clockwise in the same manner as described above. Then, the rear blade is used for the exposure opening 1.
Immediately after closing a, the operating pin 3a collides with the lower edge of the hole 1i and stops. The state at that time is the state shown in FIG.

Next, some modifications of the above embodiment will be described with reference to FIGS. In the above embodiment, one end of the shape memory alloy 10 is attached to the shutter base plate 1 and the other end is attached to the leading blade driving member 2. However, with this configuration, the end attached to the leading blade drive member 2 is always in contact with the leading blade drive member 2.
When the lead wire is attached to the stopper 12 and electrically connected, the lead wire is swung each time. It is not preferable to make such a movement in a narrow camera, and it may cause disconnection or electric leakage. Therefore, FIGS. 4 and 5 show a case where both ends of the shape memory alloy 10 are attached to the shutter base plate 1, and only the intermediate portion is bridged over the leading blade driving member 2.

First, in the modified example shown in FIG. 4, the driving member 2 for the leading blade in the embodiment is provided with a cylindrical shaft portion 2c facing the shutter base plate 1. A hole 2d penetrating in the radial direction is formed in the shaft portion 2c, and chamfered portions are formed in both outlets. And the shape memory alloy 10
Has a substantially middle portion inserted into the hole 2d. In the modification shown in FIG. 5, similarly to the modification shown in FIG. 4, the front blade drive member 2 is provided with a cylindrical shaft portion 2e toward the shutter base plate 1, and the circular shape is provided. An annular groove 2f is formed in the peripheral portion, and a substantially middle portion of the shape memory alloy 10 is hung there. It should be noted that the method of bridging the shape memory alloy is the same not only for the shape memory alloy 10 but also for the other shape memory alloys 11, 24, and 25.
It can be selectively adopted as needed.

In the above embodiment, each shape memory alloy is described as a wire-shaped one, but a strip-shaped shape memory alloy may be used. Further, in the above embodiment, the shape memory alloys 24 and 25 are separately provided, but these are used as one shape memory alloy, one end of which is attached to the front blade locking member 20, and the other end is used for the rear blade. Locking member 21
And the intermediate portion may be attached to the shutter base plate 1. Further, the above embodiment is an embodiment in which the present invention is applied to a focal plane shutter. However, the present invention separately includes a front blade, that is, an opening blade, and a rear blade, that is, a closing blade. Needless to say, the present invention can be applied to the type of lens shutter provided.
However, in this case, it is necessary to set the driving member for the front blade first after the driving member for the rear blade is set and the opening for exposure is closed by the rear blade at the time of the setting operation. In that case, each wing has one
It may be a sheet or a plurality of sheets.

[0032]

As described above, according to the present invention, the shutter device is set electrically by using a shape memory alloy instead of interlocking with the film winding device as in the prior art. Mechanical interlocking mechanism is not required, and a set member that was conventionally required for simultaneously setting the leading blade driving member and the trailing blade driving member is not required. This is extremely effective for miniaturization and motorization of the camera.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of the present invention, showing a state before setting immediately after the end of photographing.

FIG. 2 is a plan view of the embodiment of the present invention, showing a state after setting.

FIG. 3 is a timing chart for explaining the operation of the embodiment of the present invention.

FIG. 4 is a partial side view showing a partial modification of the embodiment of the present invention.

FIG. 5 is a partial side view showing a part of another modification of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shutter base plate 1a Exposure opening 1b, 1c, 1d, 1e, 1f, 1g Axis 1h, 1i, 2d Hole 1j, 1k Spring load 1m, 1n, 1p, 1s, 1t, 1u Column 1q, 1r Stopper 2 Front blade Drive members 2a, 3a Operating pins 2b, 3b Attaching portions 2c, 2e, 4b, 5b Shaft portions 2f Annular grooves 3 Rear blade drive members 4, 5 Iron piece members 4a, 5a Iron piece portions 4c, 5c Flange portions 6, 7 Compression Spring 8 Drive spring for leading blade 9 Drive spring for trailing blade 10, 11, 24, 25 Shape memory alloy 12, 13, 14, 15, 26, 27, 30 Stoppers 16, 17, 18, 19, 28, 29, 31 Screw 20 Locking member for leading blade 20a, 21a Hook 21 Locking member for trailing blade 22, 23, 34, 35 Spring 32, 33 Tensioner 32a, 33a Pin 36 Electromagnet for leading blade 3 6a, 37a Iron core member 36b, 37b Coil 37 Electromagnet for rear blade

Claims (9)

[Claims] 1. A base plate having an exposure opening, and a front blade drive that is reciprocally operable and is operated from a set position by a front blade driving spring during the exposure operation to open the exposure opening to the front blade. A member, a first shape memory alloy for actuating the leading blade drive member to a set position against the leading blade drive spring when a voltage is applied, and locking the leading blade drive member at the set position A locking member for the leading blade,
An electromagnet for a front blade for suction-holding the driving member for the front blade at a set position before releasing the locking of the locking member for the front blade, and releasing the holding force in response to a signal from an exposure time control circuit after releasing the lock. A rear blade driving member that is reciprocally operable and is operated from a set position by a rear blade driving spring during the exposure operation to cause the rear blade to close the exposure opening, and the rear blade when a voltage is applied. Shape memory alloy for actuating the driving member for the rear blade to the set position against the driving spring for the rear blade, a locking member for the rear blade for locking the driving member for the rear blade at the set position, and the rear blade And an electromagnet for a rear blade that releases the holding force in response to a signal from an exposure time control circuit after releasing the lock, after releasing the locking of the rear blade driving member at a set position before releasing the locking of the locking member. Camera system, Jitter. 2. The camera shutter according to claim 1, wherein a voltage is applied to the second shape memory alloy a predetermined time after a voltage is applied to the first shape memory alloy. . 3. One of the first shape memory alloy and the second shape memory alloy has one end attached to the base plate and the other end attached to one of the driving members. The camera shutter according to claim 1. 4. A method according to claim 1, wherein at least one of the first shape memory alloy and the second shape memory alloy has both ends attached to the base plate and both ends are hung on one of the driving members. The camera shutter according to claim 1. 5. A third shape memory alloy for actuating the front blade locking member when a voltage is applied to release the locking of the front blade driving member, and for the rear blade when a voltage is applied. The camera shutter according to any one of claims 1 to 4, further comprising: a fourth shape memory alloy that operates a locking member to release the locking of the rear blade drive member. 6. The at least one of the third shape memory alloy and the fourth shape memory alloy has one end attached to the base plate and the other end attached to one of the locking members. The camera shutter according to claim 5, wherein 7. At least one of the third shape memory alloy and the fourth shape memory alloy has both ends attached to the base plate, and the both ends are hung on one of the locking members. The camera shutter according to claim 5, wherein: 8. A shape memory alloy having both ends attached to the front blade locking member and the rear blade locking member, respectively, and having both ends mounted to the base plate, wherein a voltage is applied to the shape memory alloy. Is applied, the locking member for the front blade and the locking member for the rear blade are operated substantially simultaneously to release the locking between the driving member for the front blade and the driving member for the rear blade. The camera shutter according to claim 1, wherein: 9. A shape memory alloy having both ends attached to the base plate and two places between the both ends hooked to the front blade locking member and the rear blade locking member, respectively. When a voltage is applied, the locking member for the front blade and the locking member for the rear blade are operated substantially simultaneously to release the locking between the driving member for the front blade and the driving member for the rear blade. The camera shutter according to any one of claims 1 to 4, wherein: