JP3801700B2 - Camera shutter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera shutter including an electric device suitable for downsizing a camera.
[0002]
[Prior art]
Recently, there has been a growing demand for miniaturization and electrification of cameras, and various proposals have been made and implemented to meet this demand. Among them, regarding the electrification, the film winding operation is automatically performed by the motor, and the lens is also moved by the motor to automatically adjust the focus. Further, the electrification of the shutter device has been promoted, and the setting operation has been usually performed by the same motor in conjunction with the above-described film winding operation. In addition, the shutter device is released by pressing the release button of the camera and then using an electromagnet or a plunger in response to a signal indicating that the automatic focus adjustment has been completed.
[0003]
In addition, the shutter device includes a focal plane shutter and a lens shutter. In general, the focal plane shutter is configured such that the front blade opens the exposure opening and the rear blade closes the exposure opening during the exposure operation. However, some lens shutters include front and rear blades that function in the same manner. Thus, when the shutter device including the front blade and the rear blade is set electrically, a set member related to both the front blade drive member and the rear blade drive member is provided, and the set member is Normally, the drive members are operated to the set position by operating from the initial position to the set position in conjunction with the winding of the film.
[0004]
[Problems to be solved by the invention]
However, as described above, the demand for downsizing is extremely strong, and it has been further spurred by the appearance of IX240 cartridge film (advanced photo system film). In that case, the key point is how to reduce the size of the above-mentioned electric device to improve space efficiency. However, electromagnetic parts such as motors, electromagnets, and plungers are limited in size and are more than a certain size. However, there is a problem that the cost becomes high when trying to make it. Also, as a mechanical part, when setting the shutter device, a mechanism for interlocking with the film winding motor is required, so that not only the space problem but also the arrangement relationship of the shutter device in the camera is limited. There is a problem of receiving. Furthermore, since the set member described above needs to set both the leading blade driving member and the trailing blade driving member, the arrangement in the shutter device is naturally determined and is a relatively large component. This has become a bottleneck in downsizing.
[0005]
The present invention has been made to solve such problems, and an object of the present invention is to use a shape memory alloy as a drive source without using the above-described electromagnetic components and set members. The aim is to provide a camera shutter that is optimal for miniaturization and motorization.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the camera shutter according to the present invention is capable of reciprocating with a base plate having an opening for exposure, and is actuated from a set position by a front blade drive spring during exposure operation. A leading blade driving member that opens the opening for exposure, and a first shape memory alloy that operates the leading blade driving member to the set position against the leading blade driving spring when a voltage is applied; A leading blade locking member that locks the leading blade driving member at the set position, and the leading blade driving member is sucked and held at the setting position before the leading blade locking member is unlocked and unlocked. A leading blade electromagnet that releases the holding force in response to a signal from the exposure time control circuit later, and a reciprocating operation that is operated from the set position by the trailing blade drive spring during the exposure operation, and is applied to the trailing blade for the exposure. Close the opening A trailing blade driving member, a second shape memory alloy that operates the trailing blade driving member in a set position against the trailing blade driving spring when a voltage is applied, and the trailing blade driving member. The rear blade locking member that is locked at the set position, and the rear blade drive member that is sucked and held at the set position before the rear blade locking member is released from the exposure position control circuit. A rear blade electromagnet that releases the holding force in response to a signal; a third shape memory alloy that operates the leading blade locking member to release the locking of the leading blade drive member when a voltage is applied; And a fourth shape memory alloy that operates the trailing blade locking member to release the locking of the trailing blade drive member when a voltage is applied .
[0007]
In the camera shutter of the present invention, it is preferable that a voltage be applied to the second shape memory alloy after a predetermined time has elapsed since the voltage was applied to the first shape memory alloy.
In the camera shutter of the present invention, it is preferable that 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 of the drive member. To be attached to.
Alternatively, at least one of the first shape memory alloy and the second shape memory alloy is configured such that both ends thereof are attached to the main plate and both ends thereof are hung on one of the driving members.
[0008]
Furthermore, in the camera shutter of the present invention, preferably, prior to SL at least one of the third shape memory alloy and the fourth shape memory alloy, one end attached to said base plate, said locking member and the other end It is attached to one side.
Alternatively, at least one of the third shape memory alloy and the fourth shape memory alloy is configured such that both ends thereof are attached to the main plate and the both ends are hung on one of the locking members.
[0009]
Furthermore, in the camera shutter of the present invention, it is preferable that the third shape memory alloy and the fourth shape memory alloy are a single shape memory alloy, and both ends thereof are the leading blade locking member and the rear blade, respectively. When attached to the blade locking member and between both ends thereof are attached to the main plate, and voltage is applied to the shape memory alloy , the leading blade locking member and the rear blade locking member are approximately At the same time, the leading blade driving member and the trailing blade driving member are unlocked.
Furthermore, in the camera shutter of the present invention, preferably, the third shape memory alloy and the fourth shape memory alloy are one shape memory alloy, and both ends thereof are respectively attached to the main plate and between the both ends. Two places are hooked on the leading blade locking member and the trailing blade locking member, and when a voltage is applied to the shape memory alloy , the leading blade locking member and the trailing blade locking The members are operated substantially simultaneously, and the engagement between the leading blade driving member and the trailing blade driving member is released.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the examples shown in FIGS. Further, two modified examples of the configuration shown in the embodiment will be described with reference to FIGS. FIG. 1 is a plan view showing a state before setting immediately after the end of photographing in the embodiment, 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. 4 and 5 are partial side views for explaining some modified examples of the embodiment.
[0011]
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 has an opening 1a for exposure at a substantially central portion, but only a part on the left side is shown in the drawing. As is well known, an intermediate plate and a cover plate (not shown) are sequentially attached to the rear side of the shutter base plate 1 at a predetermined interval. The intermediate plate and the cover plate are also formed with openings having a shape similar to that of the opening 1a, and an opening for exposure as a shutter device is determined by combining these three openings. In this embodiment, a leading blade is disposed between the shutter base plate 1 and the intermediate plate, and a trailing blade is disposed between the intermediate plate and the cover plate.
[0012]
Shafts 1b, 1c, 1d, 1e, 1f, and 1g are erected on the surface side of the shutter base plate 1. Among these, the shafts 1b and 1c protrude from the back side of the shutter base plate 1, and the portion Is formed thin. Although not shown because it is well known, each of the leading blade and the trailing blade in this embodiment has a configuration in which a plurality of divided blades are pivotally supported by two arms pivotally attached to the back side of the shutter base plate 1. Each one arm (hereinafter referred to as a main arm) is pivotally attached to the shaft 1b and the shaft 1c. The shutter base plate 1 is formed with penetrating arc-shaped holes 1h and 1i.
[0013]
On the surface side of the shutter base plate 1, the front blade drive member 2 and the rear blade drive member 3 made of synthetic resin are rotatably attached to the shafts 1b and 1c. These drive members 2 and 3 are provided with operating pins 2a and 3a and mounting portions 2b and 3b, respectively. Among these, the operation pins 2a and 3a pass through the arc-shaped holes 1h and 1i, and are fitted into holes formed in the main arms of the leading blade and the trailing blade. Therefore, when the leading blade driving member 2 rotates counterclockwise, the operating pin 2a operates the main arm counterclockwise to deploy the divided blades. Conversely, when the leading blade driving member 2 rotates clockwise, the operating pin 2a is The main arm is operated in the clockwise direction so that the divided blades are superposed. On the other hand, when the rear blade drive member 3 rotates counterclockwise, the operating pin 3a operates the main arm counterclockwise to superimpose the divided blades, and the operating pin 3a operates the main arm clockwise. Sometimes split blades are deployed.
[0014]
Further, the mounting portions 2b and 3b of the respective drive members 2 and 3 are formed so as to protrude to the front side in FIG. 1, and the iron piece members 4 and 5 are respectively attached thereto. In order to clarify the configuration, the portion is shown in cross section in FIGS. The iron piece members 4 and 5 include iron pieces 4a and 5a that are attracted to the electromagnet, shafts 4b and 5b that are loosely fitted in holes formed in the attachment portions 2b and 3b, and a flange 4c, 5c, and can move in the axial direction of the shaft portions 4b and 5b. Compression springs 6 and 7 are interposed between the iron pieces 4a and 5a and the mounting portions 2b and 3b, and the flanges 4c and 5c are biased so as to contact the mounting portions 2b and 3b. is doing. Further, the leading blade driving member 2 and the trailing blade driving member 3 are urged to rotate clockwise by the leading blade driving spring 8 and the trailing blade driving spring 9, respectively. , 9 is hung on the bases of the mounting portions 2b, 3b, and the other end is hung on spring hooks 1j, 1k provided on the shutter base plate 1.
[0015]
Furthermore, one end of wire-shaped shape memory alloys 10 and 11 is attached to the leading blade driving member 2 and the trailing blade driving member 3, respectively, and the other ends thereof are attached to the shutter base plate 1. . The respective mounting methods are the same, and the respective end portions are caulked to be wound around the stoppers 12, 13, 14, and 15, and the stoppers 12, 13, 14, 15 are screwed to the screws 16, 17. , 18 and 19. These shape memory alloys 10 and 11 have a property that their length contracts when a voltage is applied to both ends thereof and returns to its original state when cooled. Therefore, although not shown, in this embodiment, the lead wire is caulked to the fasteners 12, 13, 14, 15 together with the shape memory alloys 10, 11. The shape memory alloy 10 is expanded and contracted by using the pillar 1m and the spring hook 1j provided on the shutter base plate 1 as a guide, and the shape memory alloy 11 is expanded and contracted by guiding the columns 1n and 1p provided on the shutter base plate 1. As done. Needless to say, a predetermined space is provided between the pillar 1n so that the tip of the pillar 1n does not contact the trailing blade drive member 3.
[0016]
A front blade locking member 20 and a rear blade locking member 21 are rotatably attached to the shafts 1d and 1e of the shutter base plate 1, respectively. The locking members 20 and 21 have hook portions 20a and 21a, and are urged to rotate clockwise by the springs 22 and 23. These rotations are provided on the shutter base plate 1. It is blocked by the stoppers 1q and 1r. One end of each of the wire-shaped shape memory alloys 24 and 25 is attached to each of the locking members 20 and 21, and the other end thereof is attached to the shutter base plate 1. However, one end of each of the shape memory alloys 24 and 25 is caulked to the stoppers 26 and 27 and fixed by screws 28 and 29, respectively, but the other end thereof is caulked to the common stopper 30; It is fixed with screws 31. Further, the properties of these shape memory alloys 24 and 25 are the same as those of the shape memory alloys 10 and 11, and their expansion and contraction is performed using the columns 1 s, 1 t and 1 u provided on the shutter base plate 1 as a guide. As a matter of course, when the lead wire that is caulked to the stopper 30 is connected to the plus, each lead wire that is caulked to the stoppers 26 and 27 is connected to the minus.
[0017]
Further, tensioners 32 and 33 are rotatably attached to the shafts 1f and 1g of the shutter base plate 1, respectively. These tensioners 32 and 33 are biased clockwise and counterclockwise by springs 34 and 35, respectively, and their pins 32a and 33a are always in contact with the shape memory alloys 10 and 11, respectively. 10 and 11 are kept in tension.
[0018]
Although not shown because it is well known, a mounting plate (sometimes referred to as an upper base plate) is attached to the surface side of the shutter base plate 1 so as to be parallel to the shutter base plate 1. A leading blade electromagnet 36 and a trailing blade electromagnet 37 are attached to the lower surface thereof, that is, the surface on the shutter base plate 1 side. Therefore, in FIG.1 and FIG.2, those electromagnets 36 and 37 are shown with the dashed-dotted line. The electromagnets 36 and 37 in the present embodiment are U-shaped so that the iron core members 36a and 37a attract the iron piece members 4 and 5 with two magnetic pole portions, respectively, The coils 36b and 37b are wound. However, since each of the iron core members 36a and 37a is arranged so that each of the two magnetic pole portions is perpendicular to the shutter base plate 1, only one of the magnetic pole portions is visible in the drawing.
[0019]
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 leading blade driving member 2 and the trailing blade driving member 3 are in a state where the exposure operation has been completed by the respective driving springs 8 and 9, and the photographer still holds down the release button of the camera. is there. In this state, the divided blades of the leading blade (not shown) are overlapped and stored in a position below the exposure opening 1a, and the divided blades of the rear blade are unfolded to cover the exposure opening 1a. Yes.
[0020]
From this state, when the pressing force of the release button is released, the power switch SW is turned off. Even when the power switch SW is turned off, the film winding motor Mo and the shape memory alloy 10, 11 (reference numerals SMA1 and SMA2 in FIG. 3) can be supplied with electric power. When the motor Mo is activated by the OFF signal of the power switch SW and the film winding is started, a voltage is applied to the shape memory alloy 10 (SMA1) at the same time. Therefore, the shape memory alloy 10 rapidly shrinks and becomes shorter, and rotates the leading blade driving member 2 counterclockwise against the leading blade driving spring 8. By this rotation, the leading blade drive member 2 rotates the main arm of the leading blade (not shown) counterclockwise on the shaft 1b by the operating pin 2a. As a result, the divided blades (not shown) start to operate upward while expanding.
[0021]
Immediately before the set position, the operating pin 2a pushes the back of the hook portion 20a formed on the leading blade locking member 20 and opposes the leading blade locking member 20 against the spring 22 by cam action. Rotate clockwise. At this time, since the shape memory alloy 24 is slightly loosened, it is actually necessary to prevent the shape memory alloy 24 from being detached from the column 1s. As an example, it is convenient to make the pillar 1s thicker and to form a through hole in the flank thereof and to allow the shape memory alloy 24 to pass through the hole. In this way, the operating pin 2a pushes the leading blade locking member 20, and when the pushing relation is eventually released, the leading blade locking member 20 performs a return operation in the clockwise direction by the spring 22, As shown in FIG. 2, the hook portion 20a enters the operating locus of the operating pin 2a. As can be seen from this, since the operation of the leading blade locking member 20 by the spring 22 is also regulated by the length of the shape memory alloy 24, the stopper 1q is not necessarily required.
[0022]
In this way, even when the power supply to the shape memory alloy 10 (SMA1) is cut off, the leading blade drive member 2 is maintained in its set state. And in the set state, the compression spring 6 is compressed and the iron piece part 4a of the iron piece member 4 is contacting the iron core member 36a. On the other hand, when the energization is cut off, the shape memory alloy 10 will elongate. However, as the extension elongates, the tensioner 32 is rotated clockwise by the spring 34, and the shape memory alloy 10 is always moved as shown in FIG. Since it is in a tension state, the shape memory alloy 10 does not come off from the pillar 1m and the spring hook 1j, and does not affect the operation of itself or other members by loosening. Further, in order to be able to relax without providing the tensioner 32, a groove is formed on the surface of the shutter base plate 1, and the shape memory alloy 10 is disposed in the groove. However, in that case, it is necessary to devise such that the shape memory alloy 10 does not protrude from the groove when loosened. In addition, it is possible to arrange | position in this way also about the other shape memory alloy in a present Example.
[0023]
As described above, the current is cut off from the shape memory alloy 10 (SMA1), and at the same time, a voltage is applied to the shape memory alloy 11 (SMA2). Therefore, the shape memory alloy 11 is shortened, and the trailing blade driving member 3 is rotated counterclockwise against the trailing blade driving spring 9. By this rotation, the driving member 3 for the rear blades rotates the main arm of the rear blade (not shown) counterclockwise by the shaft 1c by the operation pin 3a, and superimposes the divided blades (not shown) upward. Operate. The subsequent operation of the trailing blade driving member 3 is substantially the same as the setting operation of the leading blade driving member 2 described above, and the operating pin 3a temporarily pushes the trailing blade locking member 21 counterclockwise. Thereafter, the rear blade locking member 21 is returned by the spring 23 and locked at the set position. In this state, the compression spring 7 is compressed, and the iron piece portion 5a of the iron piece member 5 is in contact with the iron core member 37a.
[0024]
Thereafter, when the current to the shape memory alloy 11 (SMA2) is cut off, the shape memory alloy 11 expands. In this case, the tensioner 33 rotates counterclockwise to keep the shape memory alloy 11 in a tensioned state. become. In this way, all the members are in the set state shown in FIG. 2. At that time, the film winding motor Mo is also stopped and the film winding is also completed. In the above description, after the setting of the leading blade driving member 2 is completed, the setting operation of the trailing blade driving member 3 is started, but the supply voltage to the shape memory alloy 10 (SMA1) is increased. If there is no influence, the setting operation of the leading blade drive member 2 starts as in the known focal plane shutter, and after a predetermined time, the operation of the trailing blade drive member 3 is not yet completed. It is preferable to start.
[0025]
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 photometry circuit and the distance measurement circuit work, and the coils 36b and 37b of the leading blade electromagnet 36 and the trailing blade electromagnet 37 are energized. The members 36a and 37a are excited. Therefore, the iron piece portions 4a and 5a of the iron piece members 4 and 5 are magnetically attracted and held by the iron core members 36a and 37a. In addition, when the holding force is sufficiently obtained, the two shape memory alloys 24 and 25 (SMA3 and SMA4 in FIG. 3) are energized. Accordingly, the shape memory alloys 24 and 25 are shortened, and the locking members 20 and 21 are rotated counterclockwise to unlock the driving members 2 and 3.
[0026]
At this stage, the photographer can check the suitability of the photographing conditions using a known display device. If it is desired to stop the shooting, when the release button is released, the shape memory alloys 24 and 25 are first de-energized, and the locking members 20 and 21 are engaged with the driving members 2 and 3, respectively. After returning to the stop position, energization to the coils 36b and 37b is 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 works in conjunction with the operation stop signal.
[0027]
First, the exposure time control circuit cuts off the power supply to the coil 36b of the leading blade electromagnet 36. As a result, the leading blade drive member 2 is rotated clockwise by the force of the leading blade drive spring 8, and the main arm of the leading blade is actuated clockwise by the operating pin 2a. For this reason, the plurality of divided blades constituting the leading blade are overlapped to open the exposure opening 1a. On the other hand, in this process, since the leading blade driving 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 leading blade has opened the opening 1a for exposure, the operating pin 2a collides with the lower end edge of the hole 1h, and is stopped while bounce is prevented by means not shown.
[0028]
After the energization of the coil 36a of the leading blade electromagnet 36 is cut off, the energization of the coil 37b of the trailing blade electromagnet 37 is cut off after a predetermined time corresponding to the photometric result. Therefore, the trailing blade driving member 3 rotates clockwise by the biasing force of the trailing blade driving spring 9, and the operating pin 3a operates the main arm of the trailing blade in the clockwise direction. As a result, the plurality of divided blades constituting the rear blade group are expanded and the exposure opening 1a is closed. Meanwhile, since the rear blade drive member 3 pulls the shape memory alloy 11, the tensioner 33 is rotated in the clockwise direction in the same manner as described above. Immediately after the rear blade finishes closing the exposure opening 1a, 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.
[0029]
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 driving member 2 always operates together with the leading blade driving member 2 so that the lead wire is attached and electrically connected to the stopper 12. In this case, the lead wire is swung around each time. Such movement in a narrow camera is not preferable and may cause disconnection or electric leakage. Therefore, FIGS. 4 and 5 each 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 thereof is passed over the leading blade drive member 2.
[0030]
First, in the modified example shown in FIG. 4, the leading blade driving member 2 in the embodiment is provided with a cylindrical shaft portion 2 c toward the shutter base plate 1. The shaft portion 2c is formed with a hole 2d penetrating in the radial direction, and chamfered portions are formed at both outlets. The shape memory alloy 10 has a substantially intermediate portion inserted through the hole 2d. Further, in the modified example shown in FIG. 5, similarly to the modified example shown in FIG. 4, the leading blade driving member 2 is provided with a cylindrical shaft portion 2 e toward the shutter base plate 1. An annular groove 2f is formed in the peripheral portion, and a substantially intermediate portion of the shape memory alloy 10 is hung thereon. In addition, the same manner of the shape memory alloy is applied not only to the shape memory alloy 10 but also to the other shape memory alloys 11, 24, 25, and is selectively adopted according to necessity. It is possible.
[0031]
In the above embodiments, each shape memory alloy has been described as a wire shape. However, a band shape memory alloy may be used. In the above embodiment, the shape memory alloys 24 and 25 are individually provided. However, the shape memory alloys 24 and 25 are provided as one shape memory alloy, one end is attached to the leading blade locking member 20 and the other end is used for the rear blade. It does not matter if it is attached to the locking member 21 and the middle part is attached to the shutter base plate 1. Further, the above embodiment is an embodiment in the case where the present invention is applied to a focal plane shutter. However, the present invention separately provides a leading blade, that is, an opening blade and a trailing blade, that is, a closing blade. Needless to say, the present invention can also be applied to the type of lens shutter provided. In this case, however, it is necessary to start the setting operation of the leading blade driving member after the trailing blade driving member is set first and the exposure opening is closed by the trailing blade during the setting operation. In that case, each blade may be one or plural.
[0032]
【The invention's effect】
As described above, according to the present invention, when the shutter device is electrically set, it is not interlocked with the film winding device as in the prior art, but is performed with the shape memory alloy. Therefore, the mechanical interlocking mechanism with the film winding device is provided. Is unnecessary, and the setting member that has been necessary for setting the leading blade driving member and the trailing blade driving member at the same time is unnecessary, which is very advantageous in terms of space. It is extremely effective for the use of electric and electric vehicles.
[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 an 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 modification of part of the embodiment of the present invention.
FIG. 5 is a partial side view showing another modification of a part of the embodiment of the present invention.
[Explanation of symbols]
1 shutter base plate 1a exposure openings 1b, 1c, 1d, 1e, 1f, 1g shafts 1h, 1i, 2d holes 1j, 1k spring hooks 1m, 1n, 1p, 1s, 1t, 1u pillars 1q, 1r stopper 2 leading blade Driving member 2a, 3a Actuating pin 2b, 3b Mounting portion 2c, 2e, 4b, 5b Shaft portion 2f Annular groove 3 Rear blade driving member 4, 5 Iron piece member 4a, 5a Iron piece portion 4c, 5c Hut portion 6, 7 Compression Spring 8 Lead blade drive spring 9 Rear blade drive spring 10, 11, 24, 25 Shape memory alloy 12, 13, 14, 15, 26, 27, 30 Stopper 16, 17, 18, 19, 28, 29, 31 Screw 20 Front blade locking member 20a, 21a Hook portion 21 Rear blade locking member 22, 23, 34, 35 Spring 32, 33 Tensioner 32a, 33a Pin 36 Front blade electromagnet 36a, 37a Iron core portion 36b, 37b coil 37 after the wings for the electromagnet

Claims (8)

A ground plane having an exposure opening, a front blade drive member that can be reciprocated and is operated from a set position by a front blade drive spring at the time of exposure operation, and causes the front blade to open the exposure opening. A first shape memory alloy that, when applied, activates the leading blade drive member to the set position against the leading blade drive spring; and a leading blade mechanism that locks the leading blade drive member at the set position The front blade driving member is sucked and held at the set position before the locking of the locking member and the leading blade locking member is released, and the holding force is released according to the signal from the exposure time control circuit after the locking is released. A voltage is applied to the leading blade electromagnet, a trailing blade driving member that can be reciprocated and is actuated from the set position by the trailing blade drive spring during the exposure operation, and causes the trailing blade to close the exposure opening. When the rear blade drive A second shape memory alloy that moves the member to the set position against the rear blade drive spring; a rear blade locking member that locks the rear blade drive member at the set position; and the rear blade engagement A voltage is applied to the rear blade electromagnet that sucks and holds the rear blade drive member at the set position before releasing the locking member, and releases the holding force in response to a signal from the exposure time control circuit after unlocking. A third shape memory alloy that operates the leading blade locking member to release the locking of the leading blade drive member when operated, and the rear blade locking member to operate the rear when a voltage is applied. A camera shutter, comprising: a fourth shape memory alloy that releases the locking of the blade drive member .   2. The camera shutter according to claim 1, wherein a voltage is applied to the second shape memory alloy a predetermined time after the voltage is applied to the first shape memory alloy.   The at least one of the first shape memory alloy and the second shape memory alloy has one end attached to the main plate and the other end attached to one of the drive members. 2. A camera shutter according to 2.   The at least one of the first shape memory alloy and the second shape memory alloy has both ends attached to the main plate, and the both ends are hung on one of the drive members. Or the shutter for cameras of 2. The at least one of the third shape memory alloy and the fourth shape memory alloy has one end attached to the main plate and the other end attached to one of the locking members. The camera shutter according to any one of 1 to 4. The at least one of the third shape memory alloy and the fourth shape memory alloy has both ends attached to the main plate, and the both ends are hung on one of the locking members. The camera shutter according to any one of 1 to 4. The third shape memory alloy and the fourth shape memory alloy are made into one shape memory alloy, and both ends thereof are attached to the leading blade locking member and the trailing blade locking member, respectively, and between the both ends is the base plate. When the voltage is applied to the shape memory alloy, the leading blade locking member and the trailing blade locking member are operated substantially simultaneously, and the leading blade driving member and the trailing blade are operated. 5. The camera shutter according to claim 1, wherein the driving member is unlocked. The third shape memory alloy and the fourth shape memory alloy are made into one shape memory alloy, and both ends thereof are respectively attached to the main plate, and two positions between the both ends are used for the leading blade locking member and the rear blade. When the voltage is applied to the shape memory alloy, the leading blade locking member and the trailing blade locking member are operated substantially simultaneously, and the leading blade driving member and the 5. The camera shutter according to claim 1, wherein the rear blade driving member is unlocked.

Images