JPH0915676A - Camera shutter device - Google Patents

Abstract

(57) Abstract: In a shutter device provided with two light shielding means, a set aperture value and a substantial aperture value may differ greatly. In a shutter device of a camera having two light shielding means that can be opened and closed between a closed position where a lens opening is closed and a fully opened position where the lens opening is fully opened, a shutter device for the camera is provided with two light shielding means according to a release operation of the camera. Among them, the first light shielding means (8, 9) is opened from the closed position to the fully open position, and the second
There is provided control means for closing the light-shielding means (24, 25) from the stop position set in advance between the fully open position and the closed position to the closed position. After the opening operation position of the first light shielding means exceeds the position corresponding to the stop position of the second light shielding means (the position forming the lens aperture corresponding to the set aperture value),
The closing operation of the second light shielding means is started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shutter device, and more particularly to an electric shutter device.

[0002]

2. Description of the Related Art As a shutter device for a camera, for example, as proposed in Japanese Patent Application Laid-Open No. 7-56211,
Two shading means for opening and closing the lens opening by the shutter blades
There is something prepared. In the shutter device disclosed in this publication, the shutter blade of the one (first) light blocking unit is moved from the closed position where the lens opening is closed to the fully opened position where the lens opening is fully opened in response to the release operation of the camera, and the other ( The shutter / diaphragm blade of the second light shielding means is operated from the fully open position to the closed position. As a result, the shutter speed is increased as compared with the case where one light shielding unit is operated in the closed position → fully open position → closed position (particularly, when the light shielding unit is operated by rotating the step motor forward → stop → reverse). For example, if you use a large aperture for a high-intensity field and blur the background sufficiently for the main subject, or if you use daytime synchronized shooting, change the flash interlocking distance in the dark. It can be closer to the interlocking distance of.

In the shutter device proposed in the above publication, the opening operation of the first light-shielding means and the closing operation of the second light-shielding means are performed almost at the same time so that the operating positions of both the light-shielding means are set to preset aperture values. Are controlled so that the lens aperture areas corresponding to the above are matched at the obtained position. In addition to this, the exposure time is controlled by changing the operating speeds of both the light shielding means. In this way, so-called aperture priority exposure control is performed.

[0004]

However, in the shutter device proposed in the above publication, the actual lens aperture area becomes the size corresponding to the set aperture value only for a moment when the operating positions of both light shielding means coincide. Before and after that, exposure is performed only through a lens aperture (aperture aperture) smaller than the aperture area corresponding to the set aperture value. For this reason, there is a problem that a substantial aperture value becomes large and desired photographing cannot be performed.

Therefore, it is a first object of the present invention to make a set aperture value and a substantial aperture value as close as possible to each other in a shutter device having two light shielding means.

A second object of the present invention is to achieve the above-mentioned first object with a structure as simple as possible.

[0007]

To achieve the above object, in the first invention of the present application, an opening / closing operation is possible between a closed position for closing the lens opening and a full opening for fully opening the lens opening.
In a shutter device of a camera having two light shielding means,
In response to the release operation of the camera, the first light shielding means of the two light shielding means is opened from the closed position to the fully open position, and the second light shielding means is arbitrarily set in advance between the fully open position and the closed position. There is provided a control means for performing a closing operation from the stopped position to the closing position.

In such a shutter device, for example, the opening position of the first light blocking means exceeds the position corresponding to the stop position of the second light blocking means (the position where the lens aperture corresponding to the set aperture value is formed). After that, if the control for starting the closing operation of the second light shielding means is performed, the closing operation of the second light shielding means is performed after the opening operation position of the first light shielding means exceeds the position corresponding to the stop position. The aperture opening is held in the area corresponding to the set aperture value until the start of. Therefore, it is possible to bring the actual aperture value closer to the set aperture value as compared with the conventional one in which the aperture opening instantaneously has only the area corresponding to the set aperture value.

Further, in the second invention of the present application, the driving means for causing the closing operation of the second light shielding means moves the second light shielding means to the stop position before the closing operation is performed. .

According to such a shutter device, the operation of one drive means (for example, the forward rotation and the reverse rotation operation of the motor) is used to move and close the second light shielding means to the stop position. be able to. Therefore, the number of parts can be reduced and the cost can be reduced as compared with the case where a dedicated drive unit is used for each operation of the second light shielding unit.

If a step motor capable of performing a step operation in response to a pulse signal is used as the driving means, the second light shielding means can be accurately located at a desired stop position, that is, a position where a lens aperture corresponding to a set aperture value is formed. Can be stopped.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 1 to 21 show a first embodiment of the present invention, FIG. 1 is a perspective view showing a relationship of components of a shutter device of the present embodiment, and FIG. 2 is a sectional view. Is.
1 is a top plate. Reference numeral 2 denotes a first drive ring, and an inner diameter portion 2a of the first drive ring 2 is rotatably fitted to a cylindrical portion 1a formed at the center of the upper base plate 1.

Drive pins 3 and 4 are fixed to the lower surface of the first drive ring 2. Reference numeral 5 denotes a first step motor, which can perform indexing rotation at a predetermined unit rotation angle, like a known step motor.

A first pinion 6 is fixed to the output shaft of the first step motor 5. This first pinion 6
Meshes with the gear portion 2b of the first drive ring 2,
The rotational drive force of the first step motor is transmitted to the first drive ring 2. Reference numeral 7 is a first pressing plate, and as shown in FIG.
After the first drive ring 2 is fitted into the cylindrical portion 1a, it is fixed to the top surface 1i of the cylindrical portion 1a to prevent the first drive ring 2 from falling off.

A first shutter blade 8 has a hole 8a. The drive pin 3 described above is rotatably fitted in the hole 8a through an elongated hole 1g formed in the upper base plate 1.
A pin 8b is formed on the upper surface of the first shutter blade 8, and the pin 8b is slidably fitted in a cam groove 1b formed on the lower surface of the upper base plate 1.

A second shutter blade 9 has a hole 9a. The drive pin 4 described above is rotatably fitted in the hole 9a through an elongated hole 1h formed in the upper base plate 1.
A pin 9b is formed on the upper surface of the second shutter blade 9, and the pin 9b is slidably fitted in a cam groove 1c formed on the lower surface of the upper base plate 1.

Reference numeral 10 is a blade pressing plate having an opening 10a in the center. The first shutter blade 8 and the second shutter blade 9 are movably held in a plane direction in a space formed between the upper base plate 1 and the blade pressing plate 10. On the lower surface of the upper base plate 1, protrusions 1d, 1e, 1f for forming the above-mentioned gap with the blade pressing plate 10 are formed.

Reference numeral 11 is a base plate. Reference numeral 12 is a closed blade ring, and the inner diameter portion 12a of the closed blade ring 12 is
It is rotatably fitted in a cylindrical portion 11a formed in the central portion of the base plate 11. Drive pins 13 and 14 are fixed to the upper surface of the closing blade ring 12. Reference numerals 15 and 16 denote pins fixed to the arms 12c and 12d of the arms formed at three positions on the outer circumference of the closing blade ring 12.

Reference numeral 17 denotes a locking claw, which is a closing blade ring 12
It is rotatably attached to the remaining arm 12b around the pin 17a. The locking claw 17 has a tip portion 17c.
Is closed and the standing bent portion of the arm 12b of the blade ring 12 (see FIG.
Etc.) 12e, and by engaging these, counterclockwise rotation of the locking claw 17 in FIG. 12 is restricted.

Reference numeral 18 denotes a tension coil spring, one end of which is fixed to the closing blade ring 12 and the other end of which is fixed to the locking claw 17. The coil spring 18 rotates the locking claw 17 in the counterclockwise direction in FIG. Bias in the direction of. Instead of the coil spring 18, an elastic member such as a torsion spring or a compression spring may be used.

Further, the claw portion 17c of the locking claw 17 can be engaged with the locking portions 11k, 11l, 11m and 11n formed on the base plate 11, as shown in FIG. 12, for example. 1
Reference numeral 9 denotes a release pin fixed to the arm portion 17b of the locking claw 17 and can come into contact with a cam surface 20c of the second drive ring 20 described later.

Reference numeral 20 denotes a second drive ring, and an inner diameter portion 20a of the second drive ring 20 is rotatably fitted to a cylindrical portion 11j formed at the center (around the optical axis) of the base plate 11. In addition, the arm 20 formed on the second drive ring 20
The b can come into contact with the pins 15 and 16 described above.

As shown in FIG. 12 and the like, a stopper 11s is formed on the base plate 11, and this stopper 11s is formed.
By contacting the arm 12d of the closing blade ring 12 with the rotation of the closing blade ring 12 in the direction of arrow F in FIG.

Reference numeral 21 denotes a second step motor, which can perform indexing rotation at a predetermined unit rotation angle, like a known step motor.

Reference numeral 22 is a second pinion, which is fixed to the output shaft of the second step motor 21. The second pinion 22 meshes with the gear portion 20d of the second drive ring 20, and applies the rotational driving force of the second step motor 21 to the second
Tell the drive ring 20. 23 is a second pressing plate,
As shown in FIG. 2, after the second drive ring 20 is fitted into the cylindrical portion 11j of the base plate 11, the top portion 1 of the cylindrical portion 11j is
It is fixed to 1i and prevents the second drive ring 20 from falling off.

Reference numeral 26 is a torsion spring, which is shown in FIG.
As shown in FIG. 2, the coil-shaped portion is attached to the outer periphery of the protrusion 11r formed on the lower surface of the base plate 11, and one arm 26
b is locked to the protrusion 11q of the base plate 11 and the other arm 26
a is closed and locked to the pin 15 of the blade ring 12.
This torsion spring 26 is used for closing the blade ring 12.
Is urged in the direction of arrow F in FIG. As a result, the locking claws 17 are locked by the locking portions 11k, 11k of the base plate 11.
When engaged with any one of l, 11m, 11n,
The rotational position of the closing blade ring 12 is stably defined according to the position of the locking portion with which the locking claw 17 is engaged. A protrusion 11p is formed on the lower surface of the base plate 11, and the protrusion 11p is at a position where it can be engaged with the arm 26a of the torsion spring 26. In FIG. 12, the arm 26a and the protrusion 11p are not engaged, but when the closing blade ring 12 rotates in the direction of arrow F from this state, the arm 26a
It disengages from the pin 15 and engages with the protrusion 11p.

Reference numeral 24 denotes a third shutter blade, which has a hole 24a.
Having. The drive pin 13 described above is rotatably fitted into the hole 24a through an elongated hole 11g formed in the base plate 11. A pin 24b is fixed to the third shutter blade 24, and this pin 18b is slidably fitted in a cam groove 11b formed on the upper surface of the base plate 11. 2
A fourth shutter blade 5 has a hole 25a. The drive pin 14 described above is rotatably fitted in the hole 24a through an elongated hole 11h formed in the base plate 11. A pin 25b is fixed to the fourth shutter blade 25,
The pin 25b is slidably fitted in a cam groove 11c formed on the upper surface of the base plate 11. The third shutter blade 24 and the fourth shutter blade 25 are held in a space formed between the base plate 11 and the blade pressing plate 10 so as to be movable in the plane direction. On the upper surface of the base plate 11, protrusions 11d, 1 for forming the above-mentioned gap between the base plate 11 and the blade pressing plate.
1e and 11f are formed.

FIG. 3 is a sectional view taken along the line AA in FIG. In the state of FIG. 3, the opening 10a is closed by the first shutter blade 8 and the second shutter blade 9, and the first drive ring 2 (drive pins 3, 4) is rotated in the direction of arrow c from this state. Drive pin 3,
4 moves in the elongated holes 1g and 1h, respectively, and the first shutter blade 8 and the second shutter blade 9 rotate about the optical axis. At this time, the pins 8b and 9b are respectively in the cam grooves 1
Since the first shutter blade 8 is guided by the cam grooves 1b and 1c, the first shutter blade 8 rotates around the hole 8a, and the second shutter blade 9 rotates around the hole 9a so that the lens opening is formed. Expand.

Here, when the first step motor 5 is driven by one step, the first drive ring 2 rotates by γ around the optical axis. As shown in FIG. 4, the cam grooves 1b and 1c are different from those of the first drive ring 2 shown in FIG.
・ Even if it rotates by γ (that is, the first step motor 5
Even if it is driven for 3 steps), the first shutter blade 8 and the second shutter blade 9 do not rotate about the holes 8a, 9a, but rotate about the optical axis in the subsequent steps of the first step motor 5. The first shutter blade 8 and the second shutter blade 9 are formed so as to rotate about the holes 8a, 9a.

As shown in FIG. 5, the first step motor 5
In the fourth step, that is, at the rotation position of 4 · γ from the initial position of the first drive ring 2, the first shutter blade 8
The lens opening formed by the second shutter blade 9 and the second shutter blade 9 becomes a pinhole, and as shown in FIG. The opening is fully opened. At this time, both shutter blades 8 and 9 have the opening 1
The escape amount M is retracted from 0a.

In the subsequent steps of the first step motor 5, the cam grooves 1b and 1c are formed in the holes 8 while the first shutter blade 8 and the second shutter blade 9 are kept fully open.
It is formed so that it does not rotate around a and 9a but only rotates together with the first drive ring 2 around the optical axis. FIG. 7 shows the state of the twelfth step, which is the final rotational position of the first drive ring.

FIG. 8 is a graph showing the relationship between the rotation angle θ about the holes 8a, 9a of the first shutter blade 8 and the second shutter blade 9 and the number of steps of the first step motor 5, and the rotation angle. When θ becomes θ ₁ (during the 4th step), the lens aperture becomes a pinhole and the rotation angle θ
Is θ ₂ (at the 10th step), the lens aperture is fully open.

FIG. 9 is a graph showing the characteristics of the step motor. As can be seen from this graph, even if a drive electric signal is input to set the rotation speed of the step motor to, for example, a, it does not respond instantaneously, and the step motor actually reaches a certain speed a to some extent. The number of steps (3 to 4 steps in this example) is required. In the present embodiment, since the lens aperture is opened in the steps after the fourth step of the first step motor 5, there is very little error in the shutter opening speed with respect to the speed set by the electric signal. Note that the specific number of steps does not limit the present invention.

Further, as shown in FIG. 6, although the escape amount M from the opening 10a of the shutter blades 8 and 9 in which the lens openings are fully opened is small, the actual final stroke is 12 as shown in FIG. By reaching the step, the shutter blades 8 and 9 bounce at the final stroke position and the opening 10
It does not go inside a.

The light-shielding device including the first shutter blade 8, the second shutter blade 9, the first drive ring 2 and the first step motor 5 described above is called a first light-shielding device.

Further, as shown in FIG. 3, the position where the first shutter blade 8 and the second shutter blade 9 close the lens opening is referred to as a closed position, and as shown in FIGS. 6 and 7, the first shutter blade is shown. The position where 8 and the second shutter blade 9 fully open the lens opening is referred to as a fully open position.

FIG. 10 is a sectional view taken along line BB in FIG. In FIG. 10, when the closing blade ring 12 is driven in the direction of arrow D by the configuration described later, the third shutter blade 24 and the fourth shutter blade 25 rotate around the optical axis and move in the cam grooves 11b and 11c. While rotating, it also rotates around the holes 24a and 25a. FIG. 11 shows the relationship between the rotation angle α about the holes 24a, 25a of the third shutter blade 24 and the fourth shutter blade 25 and the rotation angle of the second drive ring 20, and the horizontal axis indicates the closing blade. The rotation angle of the ring 12 in the direction of the arrow D is shown, the position in FIG. 10 is 0 °, and the final stroke position is 1
0 · β °. As shown in FIG. 16, the final stroke position means the stopper 11s of the base plate 11 and the closing blade ring 1
This is the position where the second arm 12d abuts. On the other hand, the vertical axis is
The rotation angles around the holes 24a, 25a of the third shutter blade 24 and the fourth shutter blade 25 are shown.

As can be seen from this graph, the cam grooves 11b and 11c of the base plate 11 have the closing blade ring 12 of 7.
The rotation angle α of the shutter blades 24, 25 is increased during the rotation to β, and the rotation angle α of the shutter blades 24, 25 is not increased even if the closing blade ring 12 further rotates. . That is, even if the closing blade ring 12 rotates between 7 · β and 10 · β, the third shutter blade 24 and the fourth shutter blade 25 rotate only around the optical axis.

The rotation angle α _{1 in} FIGS. 10 and 11 is determined by the third and fourth shutter blades 24, 24 inside the opening 10a.
25 is a rotation angle, and the rotation angle α ₂ is a rotation angle at which the lens opening is sandwiched by the pinholes.

The light-shielding device including the third shutter blade 24, the fourth shutter blade 25, the closing blade ring 12 and the like is referred to as a second light-shielding device.

Further, as shown in FIG. 10, the position where the third and fourth shutter blades 24 and 25 bring the lens apertures to the fully opened state is called a fully opened position, and both shutter blades 24 and 25 are centered on the holes 24a and 24a. The position where the lens aperture is closed by rotating α ₂ or more is called a closed position.

12 to 16 are plan views of the second pinion 21, the second drive ring 20, the closing blade ring 12, etc., as seen from the direction of arrow E in FIG. The direction of arrow D shown in FIG. 10 is the same as the direction of arrow F in FIGS. 12 to 16.

As shown in FIG. 12, the position of the closing blade ring 12 for engaging the locking claw 17 with the locking portion 11k of the base plate 11 is the position of 5 · β in FIG. When the closing blade ring 12 is in this position, the third shutter blade 2
The area of the lens aperture (diaphragm aperture) formed by the fourth and fourth shutter blades 25 is slightly larger than the pinhole. This area is the minimum aperture area in this shutter device.

Further, as shown in FIG. 13, the position of the closing blade ring 12 for engaging the locking claw 17 with the locking portion 11n of the base plate 11 is the rotational position of 0 ° in FIG. When the closing blade ring 12 is in this position, the area of the diaphragm opening formed by the third shutter blade 24 and the fourth shutter 25 is the largest in this shutter device. This state is the same as the state shown in FIG.

In addition, the locking claw 17 is closed at a position where the locking claw 17 is engaged with the locking portions 11l and 11m of the base plate 11, and the blade ring 12 is closed.
Is positioned, the lens aperture set by the second light blocking device has an area corresponding to the position.

Next, the operation of the second light shielding device will be described.

FIG. 12 shows the initial position of the second shading device before release. When the second step motor 21 is driven in response to the release signal, the driving force of the motor 21 is transmitted to the second drive ring 20 via the second pinion 22 and rotated in the direction opposite to the arrow F. . This allows the arm 20
b pushes the pin 15 to rotate the closing vane ring 12. By controlling the driving amount of the second step motor 21, the locking portion 11 of the base plate 11 corresponding to the desired aperture value is obtained.
Any of k, 11l, 11m, 11n and locking claw 17
Can be engaged.

However, when engaging with the locking portion 11k, the second step motor 21 is not driven and is left in that position. FIG. 13 shows a state in which the locking claw 17 is engaged with the engaging portion 11n of the base plate 11 and the aperture opening is fully opened.

The locking claw 17 and the locking portion 1 of the base plate 11
The positions of the third and fourth shutter blades 24 and 25 defined by the engagement with 1k, 11l, 11m, and 11n are referred to as stop positions.

Next, the relationship between the number of steps of the second step motor 21 and the rotation angles of the second drive ring 20 and the closing blade ring 12 will be described.

When the second stepping motor 21 is driven from the state shown in FIG. 12 to rotate the second driving ring 20 in the direction opposite to the arrow F, the base plate 11 which engages with the locking claw 17 at each step. The locking part is from 11k to 11l, 11m, 11
n. The state in which the second step motor 21 is driven by 3 steps is the state shown in FIG.
This state (that is, the third and fourth shutter blades 2
The case where the stop positions of Nos. 4 and 25 are fully open positions will be described as an example.

Next, when the second step motor 21 is driven to rotate the second drive ring 20 in the direction of arrow F, as shown in FIG. 14, the cam surface 20c of the second drive ring 20 is reached.
Contacts the release pin 19 of the locking claw 17. Even in this state, the third and fourth shutter blades 24 and 25 are held at the stop position.

Then, when the second drive ring 20 is further rotated in the direction of arrow F from this state, the locking claw 17 is pushed up against the biasing force of the spring 18 by the cam surface 20c, and the locking claw 17 and The engagement with the locking portion 11n of the base plate 11 is released.

The second drive ring, as shown in FIG.
Immediately after the engagement between the engagement claw 17 and the engagement portion 11h is released, the arm 20b is brought into contact with the pin 16 to close the closing blade ring 1.
Start moving 2 in the direction of arrow F. The movement of the second drive ring 20 from the position shown in FIG. 13 to the position shown in FIG.
Rotation in the opposite direction is performed for 14 steps.

Here, the moment of inertia of the second drive ring 20 is determined by the closing blade ring 12, the third shutter blade 24,
Since it is configured to be sufficiently larger than the moment of inertia of the fourth shutter blade 25, the rotation of the second drive ring 20 thereafter is stable and less decelerated. In addition, the second drive ring 20 is changed from the position shown in FIG.
Since the error between the speed (closing speed) for narrowing the lens opening by the second light blocking device and the drive signal (electrical signal) for driving the second step motor 21 is very small during the movement to the position shown in, the closing speed is sufficiently high. Can be accelerated to. This relationship is equivalent to the relationship between the drive signal of the first step motor 5 and the opening speed in the first light shielding device.

Subsequently, when the closing blade ring 12 is rotated from 0 to 7 · β shown in FIG. 11 by 7 steps of the second step motor 21, the third shutter blade 24 and the fourth shutter blade 25 have holes 24a, The lens is rotated up to α _{3 about} 25a, and the lens opening is changed from the fully opened state to the completely closed state.

Until the rotational position of the closing blade ring 12 reaches 10 · β by driving the second step motor 21 for four steps after 7 · β, as shown in FIG. 11, the third and fourth shutter blades 24, 24 Since 25 is configured to maintain the closed state, the final stroke position is the position shown in FIG. 16, and even if the arm 12d of the closing blade ring 12 abuts on the stopper 11s of the base plate 11 and bounces, As a result, the lens aperture will not open again.

The second drive ring 20 is closed and the vane ring 12 is closed.
At the same time, to return to the initial state after reaching the position shown in FIG. 16, that is, the state shown in FIG. 12, the second step motor 21 is rotated in the reverse direction and the second drive ring 20 is rotated in the direction opposite to the arrow F. On the way, the arm 20b of the second drive ring 20
It abuts against the pin 15 fixed to the closing blade ring 12 and rotates the closing blade ring 12 in the same direction as the arrow F. Then, the second step motor 21
Is driven to return to the state shown in FIG.

FIG. 17 is a block diagram of an electric circuit used in the present embodiment, and 101 is a control circuit including a microcomputer or the like for controlling the entire sequence. Reference numeral 102 is a first step motor drive circuit for driving the first step motor 5, 103 is a second step motor drive circuit for driving the second step motor 21, and 104 is a known photometric circuit for measuring the field brightness. is there.

Reference numeral 105 is a release switch, and 106
Is an aperture setting means. The aperture setting means 106 is, for example, a switch including a pattern substrate and a contact piece,
An output signal corresponding to an aperture value that can be set in a plurality of stages (four stages in this embodiment) is output. Therefore, when the user operates the aperture setting means 106 so as to obtain a desired aperture value, the aperture setting means 106 outputs a signal corresponding thereto.

A memory circuit is included in the control circuit 101, and this memory circuit stores a time table for setting the exposure time according to the output signals of the photometric circuit 104 and the aperture setting means 106. There is.

FIG. 18 is a flow chart showing the operation of the control circuit 101. The operation of the control circuit 101 will be described below with reference to this flowchart.

In step 1, it is determined whether or not a release button (not shown) is pressed to turn on the release switch 105. If it is determined to be on, the process proceeds to step 2, and if it is determined to be off, step 1 is repeated.

In step 2, the output signal from the aperture setting means 106 is detected.

In step 3, the second step motor drive circuit 103 is responsive to the output signal from the aperture setting means 106.
The second stepping motor 21 is driven through the second driving ring 20 and the closing blade ring 12 in the direction opposite to the direction of the arrow F to set the second light blocking device to a predetermined stop position (aperture state). To do. After the setting is completed, the second step motor 21 is stopped.

In step 4, the photometric circuit 104 is operated to measure the subject brightness.

In step 5, the output signal from the aperture setting means 106 detected in step 2 and step 4
The delay time is selected from the time table in the storage circuit based on the relationship with the subject brightness measured in.
In addition, the selected delay time is calculated in step 11 described later.
In, it is used as the count-up time of the timer.

In step 6, the clock circuit 108 is reset.

In step 7, the first step motor 5 is driven via the first step motor drive circuit 102 to operate the first light shielding device from the state shown in FIG. 3 to the state shown in FIG. The first step motor 5 is driven according to predetermined drive frequency data.

In step 8, the clock circuit 108 is started and the elapsed time from the start of driving the first step motor 5 is counted.

In step 9, it is determined whether or not the first step motor 5 has been driven by the predetermined number of steps (12 steps in this embodiment, as shown in FIG. 8) via the first step motor drive circuit 102. Then, if the driving of the predetermined step is completed, the process proceeds to step 10, and if the driving of the first step motor 5 is not completed, the process proceeds to step 11.

In step 10, the first step motor 5 is stopped via the first step motor drive circuit 102.

In step 11, it is judged whether or not the count of the clock circuit 108 started in step 8 has reached the time determined in step 5, and if not, the process returns to step 9 to reach it. If yes, step 1
Proceed to 2.

In step 12, the second step motor 21 is driven through the second step motor drive circuit 103 in accordance with the predetermined drive frequency data, and the second drive ring 20 is moved in the direction of arrow F in FIG. Rotate.

In step 13, the second step motor 21 is driven through the second step motor drive circuit 103 by a predetermined number of steps (until the second drive ring 20 reaches the position shown in FIG. 16 in this embodiment). If it is determined that the driving of the predetermined step is completed, step 14
If not completed, proceed to the second step motor 21
The process returns to step 9 while continuing to drive.

In step 14, the second step motor 21 is stopped via the second step motor drive circuit 103.

In step 15, the first step motor drive circuit 10 is operated so that the first light shielding device returns to the state shown in FIG.
The driving of the first step motor is started at 2 with a predetermined driving frequency.

In step 16, it is determined whether or not the first light shielding device has returned to the position shown in FIG. 3. If it has returned to the initial position, the process proceeds to step 17, and if it has not returned, step 16 is repeated.

In step 17, the first step motor 5 is stopped via the first step motor drive circuit 102.

In step 18, the driving of the second step motor 21 is started at a predetermined driving frequency via the second step motor driving circuit 103 so that the second driving ring 20 returns to the state shown in FIG.

In step 19, it is determined whether or not the second drive ring 20 has returned to the state shown in FIG. 12, and if it has returned to step 20, if it has not returned to step 1
Repeat step 9.

In step 20, the second step motor 21 is stopped via the second step motor drive circuit 103.

19 to 22 show the lens aperture area during the shutter exposure operation when the shutter device is driven according to the above sequence. In these figures, the abscissa represents the elapsed time after the first stepping motor 5 is normally rotated in step 7, and the delay time set in step 5 is represented by T. Further, the lens aperture area formed by the first light shielding device is indicated by a, and the lens aperture area formed by the second light shielding device is indicated by b. The hatched portion in each drawing shows the area where the shutter device as a whole is actually performing exposure.

As can be seen by comparing these figures, the first
The difference between the start time of the step motor 5 and the start time of the second step motor 15, that is, the delay time T described above.
By changing, the relative position of the curve b with respect to the curve a moves to the left and right in the figure, and as a result, the exposure amount shown by the diagonal lines changes.

Here, in FIG. 19, the locking claw 17 is the base plate 1.
The case where it has engaged with 1 locking part 11n is shown.

Further, in FIG. 20, the locking claw 17 is the base plate 11
It shows the case where it is engaged with the locking portion 11m.

Further, in FIG. 21, the locking claws 17 are the base plates 11
It shows the case where it is engaged with the locking portion 11l of.

Further, in FIG. 22, the locking claw 17 is the base plate 11
It shows the case where it is engaged with the locking portion 11k of.

As can be seen from these figures, in the shutter device of the present embodiment, a predetermined time (delay time) has passed since the opening position of the first light blocking device has exceeded the position corresponding to the stop position of the second light blocking device. Since the closing operation of the second light shielding device is started after the elapse of time (determined by T), the aperture opening area corresponds to the set aperture value during most of the exposure time (region indicated by G). The exposure operation can be performed as. Therefore, a desired background blur can be obtained for the main subject.

The present invention can be applied to a camera using an image recording medium other than film, and can also be applied to a camera using an image recording medium in which photographing information can be written by a method other than magnetic recording.

Further, the present invention may be used by combining the above-described embodiments and modified examples, or their technical elements as needed.

Moreover, the present invention is applicable to various types of cameras such as a single-lens reflex camera, a lens shutter camera, a video camera, optical devices other than the camera, and other devices, and those cameras, optical devices and other devices. The present invention can also be applied to devices applied to the above or elements constituting these devices.

(Relationship Between Embodiments and Claims) A device comprising the first and second shutter blades 8 and 9 and the first drive ring 2 and the first step motor 5 for driving them in the above-mentioned embodiment is claimed. Corresponds to the first light shielding means in the range. Further, the device including the third and fourth shutter blades 8 and 9 and the second drive ring 20 and the second step motor 21 that drive them in the above-described embodiment corresponds to the second light shielding unit in the claims. . In addition, the locking claw 17 and the engaging portions 11k to 11n of the base plate 11 that engages with the locking claw 17 in the above-described embodiment are means for stopping the second light shielding means in the claims in an arbitrary stop position. Equivalent to. Further, the control circuit 101 in the above embodiment corresponds to the control means in the claims.

The above is the correspondence relationship between each configuration of the present invention and each configuration of the embodiment, but the present invention is not limited to the configurations of these embodiments, and the mechanism or the embodiment shown in the claims is not limited thereto. Any structure may be used as long as the function of the structure can be achieved.

[0095]

As described above, according to the first invention of the present application, the first light shielding means is opened from the closed position and the second light shielding means is closed at the fully open position in accordance with the release operation of the camera. The shutter device is configured to be closed from an arbitrary stop position that is previously stopped between the position and the position. For this reason,
In the shutter device of the present invention, after the opening operation position of the first light blocking means exceeds the position corresponding to the stop position of the second light blocking means (the position forming the lens aperture corresponding to the set aperture value), If the control for starting the closing operation of the second light shielding means is performed, from when the opening operation position of the first light shielding means exceeds the position corresponding to the stop position until the closing operation of the second light shielding means is started. Can hold the lens aperture in an area corresponding to the set aperture value. Therefore, the substantial aperture value can be made closer to the set aperture value as compared with the conventional one in which the lens aperture instantaneously has an area corresponding to the set aperture value only.

Further, in the second invention of the present application, the shutter device is so moved by the drive means for causing the closing operation of the second light shielding means to move the second light shielding means to the stop position before the closing operation is performed. I am configuring. Therefore, according to the present invention, the movement of the second light shielding means to the stop position and the closing operation can be performed by utilizing the operation of one driving means. Therefore, the number of parts can be reduced and the cost can be reduced as compared with the case where a dedicated drive unit is used for each operation of the second light shielding unit.

If a step motor that can perform a step operation in response to a pulse signal is used as the driving means, the second light shielding means can be stopped accurately at a desired stop position.

[Brief description of the drawings]

FIG. 1 is a perspective view of the main components of the present invention.

FIG. 2 is a sectional view of a shutter device of the present invention.

3 is a sectional view taken along the line AA of FIG. 2 (a plan view of a first light shielding device).

FIG. 4 is a plan view of a first light shielding device (a state after three-step driving of a first step motor).

FIG. 5 is a plan view of a first light blocking device (a state after driving the first step motor for four steps).

FIG. 6 is a plan view of a first light shielding device (a state after driving 10 steps of a first step motor).

FIG. 7 is a plan view of a first light shielding device (a state after 12 step driving of a first step motor).

FIG. 8 is a graph showing the relationship between the blade rotation angle of the first light blocking device and the number of steps of the step motor.

FIG. 9 is a characteristic diagram of a step motor.

10 is a cross-sectional view taken along the line BB of FIG. 2 (a plan view of a second light shielding device).

FIG. 11 is a graph showing the relationship between the blade rotation angle of the second light blocking device and the rotation amount of the closing blade ring.

FIG. 12 is an E view of FIG.

FIG. 13 is an E view of FIG.

FIG. 14 is an E view of FIG.

FIG. 15 is an E view of FIG. 2.

16 is an E view of FIG. 2. FIG.

FIG. 17 is a block diagram of an electric circuit.

FIG. 18 is a flowchart showing the operation of the control circuit.

FIG. 19 is a graph showing an exposure state.

FIG. 20 is a graph showing an exposure state.

FIG. 21 is a graph showing an exposure state.

FIG. 22 is a graph showing an exposure state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper base plate 2 1st drive ring 5 1st step motor 8 1st shutter blade 9 2nd shutter blade 11 Base plate 11k, 11l, 11m, 11n Locking part 12 Closing blade ring 15 2nd step motor 17 Locking claw 20 Second drive ring 24 Third shutter blade 25 Fourth shutter blade

Claims (4)

[Claims] 1. A shutter device for a camera having two light shielding means capable of opening and closing between a closed position for closing a lens aperture and a fully open position for fully opening the lens aperture. Of the light shielding means, the first light shielding means is operated to open from the closed position to the fully open position, and the second light shielding means is operated from a stop position preset arbitrarily between the fully open position and the closed position. A shutter device for a camera, comprising a control means for performing a closing operation to a closed position. 2. The control means starts the closing operation of the second light shielding means after the opening operation position of the first light shielding means exceeds a position corresponding to the stop position. The shutter device for a camera according to claim 1. 3. The driving means for causing the closing operation of the second light blocking means to move the second light blocking means to the stop position before the closing operation is performed. 3. A shutter device for a camera according to 1 or 2. 4. The shutter device for a camera according to claim 3, wherein the driving unit is a step motor that performs a step operation in response to a pulse signal.