JP2001100271A - Focal-plane shutter for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focal-plane shutter for a camera constituted so that the energizing force of a driving spring may not act as force making an iron piece member separate from an electromagnet when a driving member reaches an exposure actuation start position from a set position before exposure actuation. SOLUTION: A setting member 15 is provided with pressing parts 15a and 15b actuating a front blade driving member 4 and a rear blade driving member 8 to the set position, and driving spring pressing parts 15c and 15d directly tensioning a front blade driving spring 5 and a rear blade driving spring 9 from the middle of setting actuation, and restored to an initial position by the energizing force of a restoring spring 16 before the exposure actuation for the respective members 4 and 8 at the time of photographing. Since the energizing force of the springs 5 and 9 acts on the members 4 and 8 after the members 4 and 8 are temporarily stopped at the exposure actuation start position at the time of photographing, impact made when the members 4 and 8 are stopped at the exposure actuation start position is softened more than in the conventional manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a leading blade group and a trailing blade group are sequentially operated in the same direction during photographing, and exposure is performed by slits formed by slit forming blades of the two blade groups. And a focal plane shutter for a camera.

[0002]

2. Description of the Related Art In a conventional focal plane shutter of this kind, a front blade group and a rear blade group are operated by a front blade driving member and a rear blade driving member connecting them. Then, those driving members are used during the exposure operation.
By the biasing force of the leading blade drive spring and the trailing blade drive spring, respectively, they are sequentially actuated from the exposure operation start position at a predetermined timing determined by the photographing condition. By
It is designed to be operated against the biasing force of those drive springs.

By the way, prior to the start of the exposure operation, there are two types of configurations for holding each of the above-mentioned driving members at the exposure operation start position, such as a locking type and a direct type. However, the present invention relates to a focal plane shutter employing a direct type. As is well known, in the direct type configuration, an iron piece member is attached to each driving member, and immediately before the start of the exposure operation, each iron member is attracted to the respective electromagnet, so that each driving member performs the exposure operation. It is kept at the starting position. For this reason, the structure is easy to make compact as compared with the locking type, but it has various problems in manufacturing, so that various measures are required.

First, when the setting member sets the two driving members, it is impossible to make the two iron pieces contact the respective electromagnets at the same time in the final stage of the operation. . For this reason, in the normal case, each iron piece member is not fixed to each drive member, but is attached with a spring interposed therebetween, until both iron piece members can reliably contact their respective electromagnets.
Both drive members can be activated. Therefore, in the setting completed state, each driving member is in a position where it has been operated more than necessary, and each driving spring is so-called overcharged by that much, and after the contact between the iron piece member and the electromagnet, By tensioning a spring interposed between the iron piece member and the iron piece member, the relative relationship with the iron piece member is changed.

Further, in recent cameras, when photographing is completed, the film is wound up and the shutter is set immediately. In order to prevent the power battery from being wasted, energization of each of the above electromagnets is not performed at the time of setting the shutter, but is performed immediately before the next photographing is performed. Therefore, in the case of the direct type, the set member cannot be immediately returned to the pre-setting position (hereinafter, referred to as an initial position) after the end of the setting operation, and is kept at the set position until the next photographing is performed. I keep it.

Then, when the next photographing is performed,
First, each electromagnet is energized to hold each iron piece member by suction, and then the set member is returned to the initial position.After that, the energization to each electromagnet is sequentially stopped, and each drive member is exposed to light. I try to make it. However, in this manner, when the set member returns to the initial position, each drive member is interposed between the biasing force of each overcharged drive spring and the iron piece member, as described above. Due to the urging force of the tensioned spring, the actuator is slightly operated from the set position, and the operation is prevented by the iron piece already attracted by the electromagnet. The position stopped in this manner is the exposure operation start position for each driving member and each blade group. Therefore, after each driving member temporarily stops at such an exposure operation start position, the energization to each electromagnet is cut off as described above, and the exposure operation is started.

[0007]

By the way, when each driving member stops at the exposure operation start position as described above,
Due to the urging force of each spring and the inertia force of the blade group, a large impact force acts instantaneously on the iron piece member. If the attraction force of the electromagnet is not sufficient, each driving member does not stop at the exposure operation start position and runs away with the blade group. For this reason, conventionally, the power supplied to each electromagnet has been considerably increased so that such a phenomenon does not occur. However, as the electrification of cameras has progressed recently, it has become a major issue how to reduce the power supply to each electromagnet. Therefore, a proposal from such a viewpoint is described in Japanese Patent Application Laid-Open No. 9-304807. However, although the conventional ones are functionally effective, the number of parts is increased and the configuration becomes considerably complicated, so that it is not preferable when compactness and cost reduction are required. There was a problem.

Further, in this type of shutter, there is a type in which a set member is returned to an initial position by an urging force of a return spring in an initial stage of photographing. In such a configuration, usually, in the set state, a large force of the drive spring is transmitted to the set member via the drive member, and the line of action of the force substantially passes through the rotation axis of the set member. It has become. Therefore, in order for the set member to smoothly return to the initial position, the urging force of the return spring must be increased to some extent.
There was a problem that the set torque had to be increased. When the camera has not been used for a long period of time, the contact portion between the driving member and the set member is pressed by a large force of the driving spring.
As described in Japanese Patent No. 102000, an adhesion phenomenon occurs between them due to various causes, and the set member may not return to the initial position smoothly or may not return at all due to the urging force of the return spring. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a problem. It is an object of the present invention to provide a method in which a driving member reaches an exposure operation start position from a set position prior to an exposure operation. Another object of the present invention is to provide a direct-type camera focal plane shutter in which the urging force of the drive spring does not act as a force for separating the iron piece member attracted to the electromagnet from the electromagnet as in the related art. Further, another object of the present invention is that when the set member is configured to return to the initial position by the biasing force of the return spring, the set member can be smoothly moved without increasing the biasing force of the return spring. An object of the present invention is to provide a direct type focal plane shutter for a camera which can return to an initial position.

[0010]

In order to achieve the above object, a focal plane shutter for a camera according to the present invention comprises:
An iron piece member that is attracted and held by the electromagnet is attached with a buffer spring interposed. After the iron piece member comes into contact with the electromagnet during the set operation, the buffer spring is actuated to the set position while tensioning the buffer spring. A driving member that is operated to the exposure operation start position by the urging force of the buffer spring, temporarily stops, and causes the blade group to perform the exposure operation when the energization to the electromagnet is cut off; A set member that operates from an initial position during a set operation, operates the drive member to the set position by the pressing portion, and returns to the initial position after the iron piece member is attracted and held by the electromagnet during photographing. Until the middle of the set operation, one end is hung on the spring hook portion and is tensioned by the drive member so that the iron piece member is attached to the electromagnet. Immediately before touching, the one end is separated from the spring hooking portion and is tensed by being pushed by the pushing portion for the driving spring. A drive spring which is hung on a spring hook portion and which allows the drive member to perform an exposure operation. In the focal plane shutter for a camera of the present invention,
A return spring for performing a return operation from the set position to the initial position is applied to the set member, and the drive spring is configured such that the one end portion is hung on the spring hook portion of the drive member during photographing. The set member may be biased in the return operation direction via the drive spring pressing portion.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to an embodiment shown in FIGS. FIG. 1 is a plan view showing only a substantially left half when viewed from a subject side in a state where the exposure operation is completed, and shows a state immediately after the exposure operation is completed. FIGS. 2 to 9 are plan views showing only essential parts of the configuration shown in FIG. 1 to explain the respective operating states of the present embodiment.
Is for explaining a setting process, and FIG.
This is for describing a state in which when the shutter is released, the leading blade drive member and the trailing blade drive member reach the exposure operation start position prior to the exposure operation.

First, the configuration of this embodiment will be described with reference to FIG. 1. In the description, the subject side is referred to as the front side, and the image forming side is referred to as the back side. The shutter base plate 1 has an opening 1a formed in a substantially central portion of the shutter base plate 1 and having a horizontally long rectangular shape. However, as described above, since FIG. 1 shows the substantially left half of the shutter, only a part of the left side of the opening 1a is shown. As is well known, an intermediate plate and an auxiliary base plate (not shown) are attached to the rear side of the shutter base plate 1 at a predetermined interval, and a front blade is provided between the shutter base plate 1 and the intermediate plate. A group of blade chambers is formed, and a blade chamber of the rear blade group is formed between the intermediate plate and the auxiliary main plate. An opening similar to the opening 1a is also formed in the intermediate plate and the auxiliary base plate. Usually, these three openings are overlapped to regulate the exposure opening. In the example, the description will be made assuming that the shape of the opening 1a regulates the exposure opening.

On the left side of the opening 1a, three arc-shaped long holes 1b, 1c and 1d are formed.
Known cushioning members 2 and 3 having a C-shaped plane are attached to lower ends of the long holes 1b and 1c. The shafts 1e, 1f, 1g are provided on the front side of the shutter base plate 1.
Are set up, and shafts 1h, 1i, 1j,
1k is erected. Among these axes, the axis 1e and the axis 1h and the axis 1f and the axis 1j are concentrically arranged. Therefore, it is usually manufactured as the same member and fixed to the shutter base plate 1 in many cases. However, the shutter base plate 1 and the shutter base plate 1 may be integrally formed of a synthetic resin.

A driving member 4 for the leading blade is rotatably mounted on the shaft 1e, and is rotated clockwise by the urging force of a driving spring 5 for the leading blade during the exposure operation. The front blade driving member 4 is made of a synthetic resin and includes a pushed portion 4a, a driving pin 4b, an attaching portion 4c, and a cylindrical portion 4d, and the cylindrical portion 4d is fitted to the shaft 1e. Have been combined. The driving spring 5 for the leading blade has a coil portion loosely fitted in the cylindrical portion 4d, and has one end 5a.
Is hung on a member not shown, and in FIG. 1, the other end 5b is hung on the mounting portion 4c.

The drive pin 4b of the leading blade drive member 4 is provided upright on the back side and penetrates the long hole 1b of the shutter base plate 1, and has a D-shaped cross section. In addition, the tip portion has an oval shape, and its root portion comes into contact with the buffer member 2. Further, the mounting portion 4c of the leading blade drive member 4 is greatly raised on the surface side, and as shown in FIG. 1 by being broken, an iron piece member 6 has a compression spring 7 interposed therein. Installed. That is, the iron piece member 6 includes the iron piece 6a and the shaft 6
b and the head 6c, and is urged by the compression spring 7 so as to protrude the iron piece 6a to the outside. In FIG. 1, the head 6c comes into contact with the mounting portion 4c. As a result, it is in a state of not protruding any more.

A rear blade drive member 8 made of synthetic resin is rotatably mounted on the shaft 1f of the shutter base plate 1, and is rotated clockwise by the urging force of the rear blade drive spring 9 during the exposure operation. It has become so. The rear blade drive member 8 includes a pushed portion 8a, a drive pin 8b,
It has a mounting portion 8c, a cylindrical portion 8d, and a spring hook portion 8e, and the cylindrical portion 8d is fitted to the shaft 1f. Further, the rear blade drive spring 9 loosely fits the coil portion into the cylindrical portion 8d,
One end 9a is hung on a member not shown, and in FIG. 1, the other end 9b is hung on a spring hook 8e.

The drive pin 8b of the rear blade drive member 8 is provided upright on the back side and penetrates the long hole 1c of the shutter base plate 1, and has a circular cross section at the base. In addition, the tip portion has an oval shape, and its root portion comes into contact with the buffer member 3. Further, the mounting portion 8c of the rear blade drive member 8 protrudes toward the front side, and an iron piece member 10 is mounted inside the mounting portion 8c with a compression spring 11 interposed therebetween. That is, this iron piece member 10 also
In the same manner as the iron piece member 6 described above, the compression spring 1 includes an iron piece portion 10a, a shaft portion 10b, and a head portion 10c.
1, the iron piece portion 10a is urged to protrude to the outside, but in FIG.
c and does not protrude any more.

Although well-known, detailed illustration of the configuration is omitted, but a support plate is attached to the front surface side of the shutter base plate 1 at a predetermined interval in parallel with the shutter base plate 1. The supporting plate has electromagnets 12 for the leading blades.
And the rear-wing electromagnet 13 are attached. In each of the figures, only the schematic plan shape of the iron core is shown by a dashed line. The electromagnets 12 and 13 can attract and hold the iron pieces 6a and 10a of the iron pieces 6 and 10 when the coils are energized. Further, the support plate (not shown) is provided with a spring hook portion 14, which is also indicated by a dashed line in each drawing.

A set member 15 made of a synthetic resin is rotatably mounted on the shaft 1g of the shutter base plate 1, and is urged by a return spring 16 to rotate counterclockwise. The set member 15 includes pressing portions 15a, 15
b, the drive spring pushing portions 15c and 15d, and the pushed portion 1
5e, a spring hook portion 15f, a pin 15g, and a cylindrical portion 15
h, and the cylindrical portion 15h is fitted to the shaft 1g. The pin 15g provided on the rear side is inserted into the long hole 1d of the shutter base plate 1, and as shown in FIG. Clockwise rotation is prevented. Further, the return spring 16 is configured such that the coil part is the cylindrical part 1.
5h, one end 16a is hung on the spring hook 14 of the support plate (not shown), and the other end 16b is hung on the spring hook 15f of the set member 15.

Next, the structure of the front blade group and the rear blade group arranged on the back side of the shutter base plate 1 will be described. First, the front blade group includes two arms 17, 18 rotatably attached to the shafts 1h, 1i of the shutter base plate 1, and two blades 19, 19 pivotally supported in order toward their tips. 2
The blades 20 pivotally supported by the distal ends of the arms 17 and 18 are slit forming blades. The distal end of the driving pin 4b of the leading blade driving member 4 is fitted into the oval hole 17a formed in the arm 17. Further, the rear blade group includes the shafts 1j and 1 of the shutter base plate 1.
two arms 2 rotatably mounted with respect to k
1, 2 and 3 pivoted in turn towards their tips
The blades 25, 24, and 25
Are slit forming blades. And the arm 21
The tip of the drive pin 8b of the drive member 8 for the rear blade is fitted in the oval hole 21a formed in the above.

Next, the operation of this embodiment will be described. FIG.
Indicates a state immediately after the end of the exposure operation. Therefore, the leading blade drive member 4 is urged to rotate clockwise by the leading blade drive spring 5, but the stopped state is maintained by bringing the drive pin 4 b into contact with the buffer member 2. I have. At this time, the two blades 19 and 20 of the leading blade group are superimposed and stored at a position below the opening 1a. The rear blade drive member 8 is urged by the rear blade drive spring 9 to rotate clockwise. However, the stop state is maintained by bringing the drive pin 8b into contact with the buffer member 3. I have. And then,
The three blades 23, 24, and 25 of the rear blade group are deployed to cover the opening 1a. Further, the set member 15 is urged by the return spring 16 to rotate in the counterclockwise direction, but the stopped state is maintained by bringing the pin 15g into contact with the right edge of the elongated hole 1d. The position of the set member 15 is hereinafter referred to as an initial position.

When the film is wound up in the state shown in FIG. 1, the set member 15 is pushed against the pushed portion 15e by a member (not shown) on the camera body side, and the urging force of the return spring 16 is applied. Rotated clockwise against Then, first, the pressing portion 15 of the set member 15
a pushes the driven portion 4a of the leading blade drive member 4 to rotate the leading blade drive member 4 counterclockwise against the urging force of the leading blade drive spring 5. Also, by this rotation, the driving pin 4b of the leading blade driving member 4 rotates the arm 17 in the counterclockwise direction, so that the two blades 1 of the leading blade group are rotated.
9 and 20 move upward while reducing the amount of mutual overlap. Thereafter, when the amount of overlap between the slit forming blades 20 of the front blade group and the slit forming blades 25 of the rear blade group reaches a predetermined amount, the pushing portion 15b of the set member 15
Contacts the pushed portion 8a of the rear blade drive member 8. The state at that time is shown in FIG.

Therefore, thereafter, the driving member 8 for the rear blade is
Also, the pushed portion 8a is pushed by the pushing portion 15b of the set member 15.
Is pushed counterclockwise against the biasing force of the rear blade drive spring 9.
At this time, the driving pin 8b rotates the arm 21 in the counterclockwise direction, so that the three blades 23, 2 of the rear blade group are arranged.
4, 25 move upward while increasing the amount of mutual overlap. Then, the state shown in FIG. 3 is finally obtained. In the state shown in FIG. 3, as can be seen by comparing with the state shown in FIG. 9b of drive spring 9 for
Without interfering with the end portion 9b.

FIG. 4 shows a state in which the setting member 15 is further rotated clockwise from the state shown in FIG.
In this state, the other drive spring pressing portion 15c of the set member 15 comes into contact with the end 5b of the leading blade drive spring 5 from the lower right side. The pushing portion 15d has not yet contacted the end 9b of the driving spring 9 for the trailing blade. For this reason, after the state shown in FIG. 4, the driving spring 5 for the front blade is not tensioned via the driving member 4 for the front blade, but is directly tensioned by the pressing portion 15 c for the driving spring of the set member 15. Will be done. That is, the end 5b of the driving spring 5 for the leading blade
Is separated from the mounting portion 4c of the front blade drive member 4 which has served as the spring hook portion.

FIG. 5 shows a state in which the drive spring pressing portion 15d of the set member 15 is also in contact with the end 9b of the rear blade drive spring 9 thereafter. Therefore, after this state, the driving spring 9 for the rear blade also moves the driving member 8 for the rear blade.
, But is directly tensioned by the drive spring pressing portion 15d of the set member 15. That is, after the state shown in FIG. 5, both the leading blade drive spring 5 and the trailing blade drive spring 9 are tensioned by the set member 15 without mediating the respective drive members 4 and 8. become.

Thereafter, as shown in FIG. 6, the iron piece 6 of the iron piece 6 attached to the leading blade drive member 4 is used.
a contacts the electromagnet 12 for the leading blade. At this time, the iron piece portion 1 of the iron piece member 10 attached to the rear blade drive member 8
0a has not yet contacted the rear-wing electromagnet 13. Then, although not shown, in this state, the blades 19 and 20 of the front blade group are in the deployed state and completely cover the opening 1a.

FIG. 7 shows a state in which the setting member 15 has been slightly rotated clockwise from the state of FIG. This state is a state in which the iron piece portion 10a of the iron piece member 10 attached to the rear blade drive member 8 comes into contact with the rear blade electromagnet 13, which is not shown. The blades 23, 24, and 25 are in a superimposed state and are moving above the opening 1a. Further, since the leading blade driving member 4 is slightly rotated counterclockwise from the state shown in FIG. 6, the iron piece 6a of the iron piece member 6 has a compression spring 7 (FIG. 1).
2), the head 6c of the iron piece member 6 is separated from the mounting portion 4c. However, at this stage, the deviation of the relative relationship between the leading blade drive member 4 and the iron piece member 6 is still very small, and it is difficult to confirm this in the drawings.

The setting member 15 is still rotated clockwise and stopped in the state shown in FIG. That state is the shutter setting state. The above-mentioned member (not shown) on the camera body side is the pushed portion 15e of the set member 15.
In order to stop while pressing, the set member 15
Cannot return to the initial position due to the urging force of the return spring 16, and this state is maintained until the next photographing is performed. Further, from the state shown in FIG. 7, both the front blade driving member 4 and the rear blade driving member 8
1 (see FIG. 1), the iron piece members 6, 1 are rotated in the counterclockwise direction against the urging force of the iron piece members 6, 1 in this set state.
The iron pieces 6a and 10a of the "0" are considerably pushed into the mounting parts 4c and 8c, and the shaft parts 6b and 10b are accordingly
c, 8c.

At the time of the next photographing, when the release button of the camera is pressed, first, the electromagnets 12, 13 are energized, and the iron pieces 6a, 10a of the iron pieces 6, 10 are sucked and held. Next, members on the camera body side (not shown)
When the set member 15 retreats from the pushed portion 15e of the set member 15, the set member 15 is rotated counterclockwise by the urging force of the return spring 16, and starts the return operation toward the initial position. In this case, the biasing force of the leading blade drive spring 5 and the biasing force of the trailing blade drive spring 9 effectively act on the return operation.

This will be described in detail in the case of the front blade system (substantially the same in the case of the rear blade system). As is well known, in the conventional configuration, even in this set state, the end 5b of the leading blade drive spring 5 is attached to the mounting portion 4
c. Therefore, in the setting state, an extremely large force of the leading blade drive spring 5 is applied from the pushed portion 4a of the leading blade drive member 4 to the pushing portion 15a of the set member 15, and the action line of the force is applied. Had passed through approximately 1 g of the shaft. Therefore, in order to allow the set member 15 to smoothly return to the initial position during photographing, the urging force of the return spring 16 must be increased to some extent so as to overcome the above-described force.
There was a problem that the set torque had to be increased accordingly.

If the camera is not used for a long period of time, the pushed part 4a and the pushing part 15a are pressed against each other with an extremely large force. When photographing, the set member 15 may not return smoothly to the initial position due to the urging force of the return spring 16 or may not return at all (combination of the leading blade drive member 4 and the set member 15). (Relatively easy to occur when made of resin).

However, in the case of this embodiment, the force applied from the pushed portion 4a to the pushing portion 15a is only the biasing force of the compression spring 7 which is relatively small. Since the extremely large urging force acts to rotate the set member 15 in the return direction in the initial stage of the return operation of the set member 15, the set member 15
In the return operation, the return spring 16 having a small urging force can smoothly return to the initial position.

When the set member 15 starts the returning operation to the initial position in this manner, the pushing portions 15a and 15b of the set member 15 are moved by the pushed portions 4a and 4a of the driving members 4 and 8, respectively.
8a, the driving members 4 and 8 are actuated by the urging forces of the compression springs 7 and 11 (however, as is well known, the arm 18 of each blade group is moved by a weak spring called a backlash spring). , 22 are biased in the exposure operation direction (clockwise), but in such a case, the biasing force of the backlash spring is strictly considered. ), And is rotated clockwise. And
The driving members 4 and 8 are temporarily stopped by bringing the mounting portions 4c and 8c into contact with the heads 6c and 10c of the iron piece members 6 and 10, but the set member 15 continues to rotate thereafter. Continue and return to the initial position and stop. This state is the state shown in FIG. 9, and for each of the driving members 4 and 8, this position in FIG. 9 is the exposure operation start position.

By the way, in the above-mentioned process, the conventional configuration may be very inconvenient. That,
The case of the rear blade system (the case of the front blade system is also substantially the same) will be described in detail. In the conventional configuration, in the state of FIG. 8, the rear blade drive spring 9 biases the rear blade drive member 8 to rotate clockwise. Therefore, when the rear blade driving member 8 rotates from the state of FIG. 8 to the state of FIG. 9 and the mounting portion 8c comes into contact with the head 10c of the iron piece member 10, not only the restoring force of the compression spring 11 but also the strong force is obtained. The urging force of the drive spring 9 for the rear blade and the inertia force of the rear blade group based on the strong urging force also act, and an extremely large impact force is applied to the iron piece member 10. Therefore, conventionally, in order to eliminate such an impact force, a large current is supplied to the rear-wing electromagnet 13. However, in such a case, the battery is consumed greatly and the electromagnet is also increased in size. There was an inconvenience. Therefore, conventionally, various measures for improving this point have been proposed.

However, in the case of the present embodiment, in the state shown in FIG. 8, the driving member 8 for the rear blade is connected to the driving spring 9 for the rear blade.
Is not acting. Also, the rear blade drive member 8
However, the state in which the mounting portion 8c is rotated clockwise from the state of FIG. 8 and the mounting portion 8c is in contact with the head 10c of the iron piece member 10 corresponds to the state shown in FIG. The biasing force of the rear blade drive spring 9 has not yet been applied. Therefore, the impact force at the time of the contact is extremely reduced. Immediately after the contact, as shown in FIG. 9, the end 9b of the rear blade drive spring 9 pushes the spring hook 8e,
The rear blade drive member 8 is urged clockwise. At this time, since the mounting portion 8c and the head 10c are already in contact with each other, the iron piece member 10 is separated from the rear blade electromagnet 13. The force acting to cause the rear blade group is considerably smaller than the impact force of the conventional configuration because it does not involve the inertial force of the rear blade group. It should be noted that, in this embodiment, the state in which the driving member 4 for the front blade is rotated clockwise from the state of FIG. 8 and the mounting portion 4c is in contact with the head 6c of the iron piece member 6 is described in this embodiment. , Corresponds to the state shown in FIG.

After the state shown in FIG. 9 is obtained in this way, the power supply to the electromagnets 12 for the front blades is first cut off, and after a predetermined time, the power supply to the electromagnets 13 for the rear blades is cut off. As a result, the leading blade drive member 4 and the trailing blade drive member 8 are rapidly rotated clockwise one after another by the urging force of the leading blade drive spring 5 and the trailing blade drive spring 9, and each drive pin 4 b , 8b, each arm 17,
Since the slit 21 is rotated clockwise, the exposure of the image forming surface is performed by the slits formed by the two slit forming blades 20 and 25.

The driving member 4 for the front blade, which has started the exposure operation first, stops when the driving pin 4b comes into contact with the buffer member 2 at the lower end of the long hole 1b, and the front blade group is also shown. Stops by contacting a stopper that does not exist. Therefore, in the stopped state, the two blades 19 and 20 of the front blade group are set.
Are superimposed and stored at a position below the opening 1a. On the other hand, the rear blade driving member 8 that has started the exposure operation with a delay is the three blades 23, 24, 25 of the rear blade group.
When the drive pin 8b completely covers the opening 1a, the drive pin 8b comes into contact with the cushioning member 3 at the lower end of the elongated hole 1c and stops, and the rear blade group also contacts the stopper (not shown) and stops. I do. The state in which the exposure operation thus performed is completed is the state shown in FIG.

In this embodiment, the present invention is applied to both the front blade system and the rear blade system, but this does not preclude the application to only one of them. In this embodiment, the return spring is provided on the set member.
The present invention is not limited to the one provided with such a return spring. Further, in this embodiment, the driving member for the front blade and the driving member for the rear blade are set by one set member, but the set members may be separately provided.

[0039]

As described above, according to the focal plane shutter of the present invention, the drive member is moved from the set position to the exposure operation start position prior to the exposure operation only by providing the drive member with the drive spring pressing portion. When the pressure reaches the limit, the urging force of the drive spring and the inertial force of the blade group based on the urging force do not act as a force for separating the iron piece member attracted to the electromagnet from the electromagnet as in the conventional case. Can be
This is extremely effective for power saving, cost reduction, and compactness. Further, even when the set member is configured to return to the initial position by the biasing force of the return spring, the drive spring biases the set member in the return operation direction in the initial stage of the return operation. Therefore, the set member can be smoothly returned to the initial position without increasing the urging force of the return spring.

[Brief description of the drawings]

FIG. 1 is a plan view of an example showing an approximately half of a left side when viewed from a subject side, showing a state immediately after an exposure operation is completed.

FIG. 2 is a plan view showing a main part of the embodiment, and shows a state immediately after a setting operation is started.

FIG. 3 is a plan view of the embodiment shown in the same manner as FIG. 2 and shows a state when the setting operation has slightly advanced from the state in FIG. 2;

FIG. 4 is a plan view of the embodiment shown in the same manner as FIGS. 2 and 3, wherein the setting operation proceeds slightly from the state of FIG. 3, and a part of the setting member is moved to the leading blade driving spring. It shows the state at the time of contact.

5 is a plan view of the embodiment shown in the same manner as FIGS. 2 to 4, wherein the setting operation proceeds slightly from the state of FIG. 4, and another part of the set member is driven by the rear blade; This shows a state when the spring comes into contact with the spring.

6 is a plan view of the embodiment shown in the same manner as FIGS. 2 to 5, wherein the setting operation proceeds slightly from the state of FIG. 5, and the iron piece member attached to the leading blade driving member is It shows a state when it comes into contact with the iron core of the electromagnet for the leading blade.

7 is a plan view of the embodiment shown in the same manner as FIGS. 2 to 6, wherein the setting operation proceeds slightly from the state of FIG. 6, and the iron piece member attached to the rear blade drive member is It shows a state when it comes into contact with the iron core of the electromagnet for the rear blade.

FIG. 8 is a plan view of the embodiment shown in the same manner as FIGS. 2 to 7, showing a set state in which the setting operation slightly advances from the state of FIG. 7 and stops.

9 is a plan view of the embodiment shown in the same manner as FIGS. 2 to 8, when the camera is released, prior to the exposure operation, the driving member for the front blade and the driving member for the rear blade. Indicates a state where the exposure stops at the exposure operation start position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shutter base plate 1a Openings 1b, 1c, 1d Slots 1e, 1f, 1g, 1h, 1i, 1j, 1k Shaft 2, 3 Buffer member 4 Driving member for leading blade 4a, 8a, 15e Pushed portion 4b, 8b Driving pins 4c, 8c Attaching portions 4d, 8d, 15h Tube portion 5 Driving springs for leading blades 5a, 5b, 9a, 9b, 16a, 16b End portions 6,10 Iron piece members 6a, 10a Iron piece portions 6b, 10b Shaft portions 6c, 10c Head 7, 11 Compression spring 8 Rear blade drive member 8e, 14, 15f Spring hook portion 9 Rear blade drive spring 12 Front blade electromagnet 13 Rear blade electromagnet 15 Set member 15a, 15b Pushing portion 15c, 15d Pushing portion for drive spring 15g Pin 16 Return spring 17, 18, 21, 22 Arm 17a, 21a Hole 19, 20, 23, 24, 25 Blade

Claims (2)

[Claims] An iron piece member attracted and held by an electromagnet is attached via a buffer spring. When the iron piece member comes into contact with the electromagnet during set operation, the iron piece member is actuated to the set position while tensioning the buffer spring and photographing. A driving member that operates to the exposure operation start position by the urging force of the buffer spring after the energization of the electromagnet and temporarily stops and causes the blade group to perform the exposure operation when the energization to the electromagnet is cut off; A spring pressing portion, which is operated from an initial position at the time of a set operation, and the driving member is operated to the set position by the pressing portion, and at the time of photographing, the iron piece member is attracted and held by the electromagnet and the initial position The set member that returns to the above, and the iron piece member is tensioned by the drive member while one end is hung on the spring hook portion until the middle of the set operation. Immediately before coming into contact with the electromagnet, the one end portion is separated from the spring hook portion and is tensed by being pushed by the drive spring pushing portion. A focal spring for a camera, comprising: a drive spring whose section is hung on the spring hook section so that the drive member can perform an exposure operation. 2. A return spring for performing a return operation from a set position to an initial position is hung on the set member, and the drive spring has one end at the time of photographing, the one end of which is the spring hook portion of the drive member. 2. The focal plane shutter for a camera according to claim 1, wherein the set member is urged in the return operation direction via the driving spring pressing portion until the setting member is engaged.