JP2001272711A - Shutter blade for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shutter blade for a camera constituted so that shutter speed is made higher whale realizing the miniaturization of a shutter and suppressing power consumption and an exposure aperture is opened/closed by relatively actuating two blades. SOLUTION: The blades 14 and 15 are formed so that 1st edge parts 14b and 15b and 2nd edge parts 14c and 15c may be respectively continued by 1st bending points 14d and 15d. At the initial stage of closing operation, an aperture part 2a is closed by the 1st edge parts 14b and 15b and the 2nd edge parts 14c and 15c. After passing the 1st bending points 14d and 15d, the aperture part 2a is closed by the 2nd edge parts 14c and 15c. By setting the rate of change Δθ2 of a crossing angle at that time to be smaller than the rate of change Δθ1 of the crossing angle at the initial stage of the closing operation, the 2nd edge parts 14c and 15c in a linear state where they are made to come close to each other in a closing direction from the 1st bending points 14d and 15d are respectively formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a blade of a camera shutter in which a plurality of blades relatively reciprocate to open and close an exposure opening to expose an imaging surface of an imaging element and a film.

[0002]

2. Description of the Related Art A shutter of a type in which two blades are pivotally attached to a main plate and are operated to open and close an exposure opening relatively in response to reciprocating rotation of a driving means. It is also used for digital cameras using an image sensor and cameras using a film. When used in digital cameras,
It is known that the blades return to an open position after closing an exposure opening by a driving means.

[0003] One example of this is disclosed in Japanese Patent Laid-Open No. 10-22
There is one disclosed in Japanese Patent No. 1740. In this conventional example, the shutter blades 4 and 5 (blades) are pivotally supported on the pins 1a and 1b of the upper base plate 1 at positions lateral to the exposure opening AP. In addition, output pin 6f
The (drive pin) penetrates through the upper base plate 1 and the middle base plate 2 and engages with the long holes 4 a and 5 a formed in the shutter blades 4 and 5. When a positive pulse current is supplied to the coil 6c of the moving magnet 6 from the initial state, the magnet 6e rotates counterclockwise to bring the output pin 6f into contact with the ferromagnetic pin 1d and to magnetize it. And stop.
When the output pin 6f rotates counterclockwise in this manner, the two shutter blades 4 and 5 pivotally supported at positions lateral to the exposure opening AP (exposure opening) change from the shielded state (closed state) to the open state (closed state). After being operated (open state), it is held, so that display on the liquid crystal finder is enabled.

After that, when the release switch 14 is turned on, after a predetermined exposure time elapses from the time when the discharging operation of the CCD 12 is completed, a negative pulse current is supplied to the coil 6c to rotate the magnet 6e clockwise. Then, the output pin 6f is brought into contact with the ferromagnetic pin 1c and magnetically attached to stop. Therefore, with the clockwise rotation of the output pin 6f, the shutter blades 4, 5
P is shielded and held. When a positive pulse current is again supplied to the coil 6c after one photographing operation is completed in this way, the shutter blades 4, 5 open the exposure aperture AP by the output pin 6f, and display on a liquid crystal monitor or the like. Next, release switch 1
This is to wait until 4 is turned on.

[0005]

By the way, in recent years, the number of pixels of the image sensor has been increasing remarkably. However, unless the pixel density is generally increased, the imaging area of the image sensor will increase. When an imaging element having an increased imaging area is used for reasons such as cost reduction of the camera, the aperture of the exposure aperture increases with an increase in the imaging area, so that the operation amount of the blade increases. Will be. as a result,
There is a problem that the operating speed of the blade must be increased. In particular, in the case of a shutter for a digital camera using an imaging element having no shutter function, the shutter speed at the time of closing operation affects the exposure amount, so that increasing the shutter speed is an important problem. Was.
In addition, since the size of the camera itself is still strongly required even when the diameter of the exposure aperture is increased, there has been a problem that the shutter speed must be increased while maintaining the miniaturization of the shutter.

In order to solve such a problem, as one method of solving such a problem, the shutter speed is increased by increasing the current supplied to a motor used as a driving source for the blades to increase the driving force of the motor. There is also a way to make it happen. However, since the digital camera also consumes power for display on the liquid crystal monitor and image storage as described above, there is a demand for minimizing power consumption. For this reason, it is not possible to adopt a method for increasing the shutter speed by increasing the current supplied to the motor.

Further, even if the driving force of the motor is increased by any method, as shown in the above-mentioned publication, the edge of the shutter blades 4 and 5 on the side of opening and closing the exposure opening AP is (opening edge). Portion), if formed linearly from the vicinity of the pivot portion to the tip portion, when the shutter blades 4, 5 open and close the exposure opening AP, these edges may intersect the rotation angle of the output pin 6f. The change rate of the intersection angle formed by the above will be constant.
Therefore, in the shutter blades 4 and 5 having such a shape,
There has been a problem that there is a limit in increasing the shutter speed, and it is not suitable for increasing the shutter speed.

Further, in the case of such a blade having an opening forming edge formed in a straight line, the blade bounces before stopping completely at the shielding position, and the exposed opening AP near the tip of the shutter blades 4 and 5 is temporarily removed. There was also a problem that it was open to the public.

In a camera using a film, a shutter having a large exposure aperture, such as a shutter of a so-called large-format camera, uses a motor as a driving force source similarly to the case of the digital camera described above. When the opening and closing operation of the blade is performed, it is difficult to increase the driving force by increasing the supply current to the motor, and there is a limit in increasing the shutter speed due to the problem of the shape of the blade edge. There was such a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to obtain a high shutter speed while maintaining a small size and low power consumption of the shutter. To provide a shutter blade for a camera.

[0011]

In order to achieve the above-mentioned object, a blade of a camera shutter according to the present invention comprises a main plate having an opening, and one end rotating at a side position of the opening. A camera shutter comprising two blades which are pivotally mounted so as to be closed so that their opening forming edges sequentially cross each other from the pivot side to the tip side, and a motor for driving the blades. The opening forming edges of the two blades have at least one bending point, and the opening forming edges are respectively formed so as to approach each other in the closing operation direction from the bending point toward the tip side of the blade. To be.

Further, in the blade of the camera shutter according to the present invention, the rate of change of the intersection angle formed by the opening forming edges of the two blades becomes small immediately after passing through the bending point during the closing operation. If the straight edges are formed from the bending point on the front end side toward the tip of the blade, the shutter speed can be further increased.

Further, in the blade of the camera shutter of the present invention, the opening is circular, and the bending point on the foremost side coincides with the contact point of the tangent of the opening passing through the center of rotation of each blade. In this case, the shape of the opening forming edge of the blade is optimized, so that it is possible to maintain the shutter without affecting the downsizing of the shutter.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to two illustrated embodiments. The drawings are shown in FIGS.
Shows a first embodiment, and FIG. 8 shows a second embodiment.

[First Embodiment] A first embodiment will be described with reference to FIGS. FIG. 1 is a plan view showing an initial state when viewed from the subject side, and shows a state in which the blades are open. FIG. 2 is a cross-sectional view showing an overlapping relationship of main members. FIG. 3 is a plan view of the inside of the blade chamber during the closing operation, and shows a state where the edge of the blade reaches the edge of the exposure opening. FIG. 4 is a plan view of the interior of the blade chamber showing an initial state in which the closing operation has proceeded more than the state of FIG. FIG.
FIG. 6 is a plan view of the inside of the blade chamber showing a state of an end stage in which the closing operation further proceeds after the state of FIG. 4. FIG. 6 is a plan view showing a state immediately after the closing operation is completed. FIG. 7 is a timing chart showing the exposure characteristics. In addition, in order to clarify the difference between the blades of the prior art and the present invention, the blades are shown in FIGS. 3 to 5 in an overlapping manner, and in FIG. 3 shows both exposure characteristics.

First, the configuration of the present embodiment will be described mainly with reference to FIGS. The base plate 1 and the auxiliary base plate 2 are both made of synthetic resin, and have circular openings 1a and 2a around the optical axis at the center. The smaller diameter of the openings 1a and 2a regulates the size of the exposure opening. In this embodiment, the openings 1a and 2a are arranged so as to be concentric. Exposure opening is the same as the opening 1a
And the opening 2a, and these circumferential portions are the edges of the exposure opening. The base plate 1 and the auxiliary base plate 2 are attached to each other with screws or the like, not shown, and a blade chamber is formed between them. further,
These ground plates 1 and 2 are provided with mounting portions (not shown) so that the camera has the ground plate 1 on the subject side and the auxiliary ground plate 2 on the imaging surface side or film surface side of the image sensor. Attached. Therefore, in the following description, the subject side is referred to as the front side, and the imaging surface side or the film surface side of the imaging device is referred to as the back side.

In FIG. 1, a motor 3 of a current control system called a moving magnet type motor is mounted on the front side of the main plate 1. This moving magnet type motor is of a type that rotates by a predetermined angle in the forward direction when energized in the forward direction to the coil of the stator, and in the opposite direction when energized in the reverse direction. Therefore, the rotor 4 is made of a two-pole permanent magnet that is magnetized in the radial direction, and the boundary between the two poles is, as shown by a dashed line in FIGS. 4a and the drive pin 4b. Also, the rotor 4
The drive pin 4b extends parallel to the rotary shaft 4a at the radial position of the rotary shaft 4a.
rotor 4 by outsert processing of synthetic resin with
And are integrally formed. Incidentally, as a rotor of this type of motor, one in which the rotating shaft 4a and the drive pin 4b are also made of a permanent magnet is known, but in the present invention, it is assumed that the rotor is formed in such a manner. It does not hinder.

Further, the stator frame of the present embodiment is composed of an upper frame 5 and a lower frame 6 made of synthetic resin. The upper frame 5 and the lower frame 6 are used for bearing the rotating shaft 4a.
(Only one is shown in FIG. 2). Further, an arc-shaped long hole 6a is formed in the lower frame 6, and the drive pin 4b is penetrated therethrough. Further, the base plate 1 and the auxiliary base plate 2 are also formed with a long hole 1b and a long groove 2b having substantially the same shape, and the driving pin 4b penetrates the long hole 1b and has a tip portion inserted into the long groove 2b. Accordingly, the drive pin 4b is driven by the rotation of the rotor 4 to rotate the slots 1b, 6
a, it can be operated by a predetermined angle in any of the long grooves 2b.
The operating angle range is thereby restricted.
The coil 12 is wound so as to cover the bearing portions of the upper frame 5 and the lower frame 6.

The upper frame 5 is formed in a cylindrical shape, and a cylindrical yoke 7 is fitted to the outer peripheral portion thereof. Further, as shown in FIG. 1, four iron pins 8, 9,
10 and 11 (hereinafter collectively referred to as holding means) are press-fitted into slots formed in the upper frame 5 so as to face the peripheral surface of the rotor 4. Iron pins 8, 9 and iron pins 10,
In FIG. 1, the coil 12 passes through the rotating shaft 4a and
Are arranged at positions symmetrical with respect to a horizontal line substantially orthogonal to the winding row. The motor 3 configured as described above is mounted on the main plate 1 by two screws 13.

Next, the configuration inside the blade chamber will be described. The base plate 1 has two shafts 1f, 1 at side positions of the opening 1a.
g is formed integrally with the main plate 1 by molding. Each of these tips is fitted into a hole formed in the auxiliary base plate 2. In addition, the wings 14 and 15
The blades 14 and 15 are relatively configured to operate, and these blades 14 and 15 are rotatably supported by shafts 1 f and 1 g, respectively, and are formed on the blades 14 and 15. The drive pins 4b described above are connected to the holes 14a and 15a. Accordingly, in FIG. 1, when the rotor 4 rotates counterclockwise, the blades 14, 15 are driven by the drive pin 4b.
Performs the closing operation of the openings 1a and 2a, and thereafter, when the rotor 4 rotates clockwise, the blades 14 and 15 perform the opening operation of the openings 1a and 2a. Contrary to the above, a hole may be provided in one of the base plates, and a shaft may be provided in the blades 14 and 15.

3 to 5, the prior art blades 16 and 17 and the blades 14 and 15 of the present invention as shown in the above publication are overlapped for explanation. , These differing sites are indicated by dashed lines. Therefore, the blades 16 and 17 are rotatably supported by the shafts 1 f and 1 g, and the driving pins 4 b are connected to the long holes 16 a and 17 a formed in the blades 16 and 17. Will be. In addition, the blades 16 and 1
As shown by the alternate long and short dash line and the solid line, the opening forming edge of 7 passes through the centers of the shafts 1f and 1g from the side supported by the shafts 1f and 1g to the tip end, respectively, at the exposure opening edge. First linear edges 16b, 17b formed as tangents to a certain opening 2a are formed at least within a range for opening and closing the opening 2a. In FIG. 3, the shafts 1f,
A part of a tangent line of the opening 2a passing through the center of 1g and an operation trajectory of the first bending points 14d and 15d, which will be described later, are indicated by a two-dot chain line. Indicated by "+".

On the other hand, the opening forming edges of the blades 14 and 15 of the present invention are on the side supported by the shafts 1f and 1g.
A first linear edge 14 formed as a tangent to the opening 2a, which is an exposure opening edge, passing through the centers of the axes 1f and 1g, respectively.
The b and 15b are the same as the blades 16 and 17 described above in that they are formed. However, the first edge portions 14b, 1
5b, the blades 14 and 15 are provided with openings 2 on the tip side.
a are formed so as to approach each other in the direction in which the first edge 14a is closed, and the first edges 14b, 15b and the second edges 14c, 15c are formed.
Are different from each other in that they are made continuous by the first bending points 14d and 15d.

In addition, the opening 2a is provided with the first
The edges 14b, 15b and the second edges 14c, 15c move from the side supported by the shafts 1f, 1g toward the distal end.
Since the first bending points 14d and 15d are closed by sequentially intersecting, the first bending points 14d and 15d are formed by the edges 14b and 14c of the blade 14 and the edges 15b and 15c of the blade 15
What is necessary is just to provide each in the range which opens and closes the opening part 2a. Therefore, in the case of this embodiment, the first
The bending points 14d and 15d are provided so that the tangent of the opening 2a passing through the centers of the shafts 1f and 1g, respectively, coincides with the point of contact with the circumference of the opening 2a which is the exposure opening edge. Since the shape of the blades 14 and 15 is optimized, the size of the shutter can be maintained without affecting the size of the shutter. Furthermore, the motor 3 in the present embodiment and the moving magnet 6 in the prior art have substantially the same configuration and the same operating load, so that they can be maintained without affecting the power consumption. It has become.

The blades 14, 15 (blades 16, 17)
Are a hole forming a rotation center rotatably supported on the shafts 1f and 1g, a long hole connected to the drive pin 4b, and an opening forming edge portion, respectively. Are arranged so as to be line-symmetric with respect to a straight line that passes through. for that reason,
In this embodiment, the blades 14, 15 (the blades 16, 1
7) have the same shape, and one of the shutter blades is arranged upside down. However, this is because the pair of blades is manufactured so as to be a common part, and the above-described portions other than the hole, the long hole, and the opening forming edge are formed in different shapes. No problem.

Next, the operation of this embodiment will be described. The present invention can be applied to a digital camera using an image sensor and a camera using a film.
The following description of the operation is for the case where the present invention is applied to a digital camera. There are shutters for digital cameras generally referred to as a normally open system, and shutters generally referred to as a normally closed system.
The main difference is whether the blades are closed when the camera is not in use. In either type of shutter, when the release button of the camera is pressed and the release switch is turned on, the shutter mode is switched from the display mode to the shooting mode while the shutter blades are kept open, and the To give a shooting start signal.

When the photographing is completed, the shutter blade is closed by the photographing end signal and the exposure opening is completely closed, instead of giving the photographing end signal to the image sensor. It is common to end with Thereafter, when the transfer of the imaging information to the storage device is completed in the state where the blade is closed, the blade is operated again in the open state, and switches from the photographing mode to the display mode to prepare for the next photographing. ing. The present invention is a shutter that can be adopted in both the above-described normally open system and the normally closed system. However, the present embodiment describes a case of a shutter of a type referred to as the above-described normally open system. I do.

First, FIG. 1 shows an initial state in which the power supply of the camera is turned on, and in the timing chart of FIG. In this state, since the blades 14 and 15 open the openings 1a and 2a, the state is exactly the same as when the camera is not in use and the power supply is turned off. Reference numeral 12 denotes a non-energized state. However, in spite of such a state, the rotor 4 is surely maintained in this state by the action of its own magnetic force unless there is a certain amount of time. Even if there is, it can be returned to this state immediately.

That is, in this state, S
The magnetic attraction acting between the pole and the iron pin 10 is
The magnetic attractive force acting between the S pole and the iron pin 11 is greater than the magnetic attractive force acting between the N pole and the iron pin 8, and the magnetic attractive force acting between the N pole and the iron pin 8 acts on the N pole and the iron pin 9. Since the arrangement is larger than the magnetic attraction force, the rotor 4 is given a clockwise rotation force. For this reason,
Although the drive pin 4b pushes the shutter blades 14 and 15 in the opening operation direction, the drive pin 4b comes into contact with the lower end surface of the long groove 2b, and the operation is prevented. In this embodiment, four iron pins 8, 9, 10, and 11 are arranged. However, the number of such iron pins is intended to increase the magnetic attraction acting between the iron pins and the rotor. This is the case, and the number is not particularly limited to four.

In the state shown in FIG. 1, an image of a subject can be displayed on display means such as a liquid crystal monitor. Then, when the release switch is turned on during photographing, a photographing start signal is given to the image sensor. Thereafter, when a predetermined exposure time elapses, the coil 1 of the motor 3
2, the rotor 4 starts rotating counterclockwise against the magnetic attraction acting between the rotor 4 and the holding means (iron pin). Therefore, with the rotation of the rotor 4, the drive pin 2b relatively operates the shutter blades 14, 15 to start the closing operation of the opening 2a. Thereafter, the first edges 14b, 15b of the blades 14, 15 of the present invention and the blades 16, 17 of the prior art
FIG. 3 shows a state in which the first edge portions 16b and 17b reach the exposure opening edge of the opening 2a. still,
In the closing operation, after the state shown in FIG. 3, the stage where the edges on the side where the blades 14 and 15 are pivotally intersected with the first bending points 14 d and 15 d as a boundary is referred to as an initial stage. The stage at which the edges on the tip side intersect is referred to as an end stage.

In the state shown in FIG. 3, the first edges 14b, 15b of the blades 14, 15 and the first edges 16b, 17b of the blades 16, 17 still cover the opening 2a. Although not shown, from the next moment, these edges will each begin to rapidly cover the opening 2a.
FIG. 4 shows such an initial state of the closing operation. At this time, the blades 14 and 15 of the present invention have the first edges 14b and 15b and the second edges 14c and 15c. So that the second edge portion 14 is compared with the blades 16 and 17.
The openings 2a are covered more by c and 15c.
That is, the first edge 14b of the blade 14 (the first edge 16b of the blade 16) and the blade 15 with respect to the rotation angle of the drive pin 4b.
When the rate of change of the cross angle formed by the (first edge 17b of the blade 17) first edge portion 15b and [Delta] [theta] _1, the same change rate [Delta] [theta] in
_Since the closing amount of the opening 2a is larger in the blades 14 and 15 than in the blade 1, as shown in FIG.
The exposure characteristics at the initial stage when the openings 4 and 15 start closing the opening 2a are steeper than those of the blades 16 and 17 of the prior art.

Thereafter, when the rotor 4 further rotates in the counterclockwise direction, this time, at the end stage of the closing operation as shown in FIG. , 15c intersect. In this case,
Than the rate of change [Delta] [theta] ₁ of the intersection angle as described above, the driving pin 4b
Change rate Δθ _{2 of the} intersection angle between the second edge 14c of the blade 14 and the second edge 15c of the blade 15 with respect to the rotation angle of
Since the direction of which is to become such a relationship smaller (Δθ _1> Δθ _2), than the initial stage of the closing operation described above, the exposure characteristic becomes steeper. Therefore, the operation time of the shutter blades 14 and 15 of the present invention from the start of closing the opening 2a to the end of closing the opening 2a is shortened. In other words, the shutter speed can be increased.

Thereafter, the rotor 4 further rotates in the counterclockwise direction, comes into contact with the upper end face of the long groove 2b formed in the auxiliary base plate 2 and stops, but at this time, the blades 14, 1
In FIG. 5, since the second edge portions 14c and 15c are respectively formed, the amount of overlap on the tip side increases, so that even if the bouncing occurs before the stop, the opening portion 2a is temporarily opened. There is no fear. Then, after that, the stopped state is held by the above-mentioned holding means, and the state immediately after the end of the closing operation in which the stopped state is held in this way is shown in FIG.

Next, when the imaging information is stored in the storage device after the opening 2a is closed, the blades 14, 15 are operated in the reverse of the above-described closing operation in preparation for the next photographing. Then, the opening 2a is relatively opened by the drive pin 4b. In this case, contrary to the above-described closing operation, the energization in the reverse direction is performed on the coil 12 of the motor 3, so that the rotor 4 is held in the closed position by the above-described holding means. It will be rotated clockwise against the holding force.

Then, as shown in FIG.
The opening portions are sequentially formed from the second edge portions 14c and 15c of
2a will start to open, at this time, as described above
Change rate of intersection angle Δθ₁Than the rate of change Δθ_TwoIs better
The relationship (Δθ ₁> Δθ_Two)It has become
Therefore, the blades 14 and 15 are rapidly opening the opening 2a.
Will be. And such a state is shown in FIG.
As shown in FIG.
It is steep. Then, the rotor 4 is further turned clockwise.
Then, as shown in FIG. 4, the wings
The roots 14 and 15 are composed of the first edges 14b and 15b and the second edges 1
4c and 15c to open the opening 2a.
Become.

[0035] Also in this case, the shutter blades 14 and 15 toward the second edges 14c, amount that 15c is formed, the blade 15 with respect to the change rate [Delta] [theta] ₁ of the intersection angle as described above, the opening Since the opening amount of the portion 2a is large, the exposure characteristic is steeper than that of the blades 16 and 17, as shown in FIG. Accordingly, the operation time from the start of opening the opening 2a to the end of the opening is shortened, so that the shutter speed during the opening operation can be increased. And
Such opening operation of the blades 14 and 15 is stopped by the drive pin 4b abutting on the lower end of the long groove 2b, and the power supply to the coil 12 of the motor 3 is cut off, as shown in FIG. Return to the initial state.

Note that, as shown in FIG.
The opening operation of the blades 4 and 15 is slightly delayed until the opening 2a starts to be opened, compared with the opening operation of the blades 16 and 17, but this delay time is caused by the transfer of the imaging information to the storage device performed before the opening operation. The opening operation is an extremely short time compared to the time, and the opening operation is for enabling display on the liquid crystal monitor or the like until the next photographing, so that the exposure amount is not affected unlike the closing operation. In addition, feathers 14, 15
Does not affect the exposure for the reasons described above, and even if there is a bounce affecting the exposure, in this case, mainly the blade 14 , 15 cover the opening 2a, so that the generation conditions are at least the same as those of the blades 16, 17 in the prior art. Therefore, such a delay time at the beginning of the opening operation and a bound generated at the end of the opening operation are not practically problematic.

Second Embodiment Next, a second embodiment will be described with reference to FIG. FIG. 8 shows an initial stage of the closing operation in the blade chamber shown in FIG. 4 of the first embodiment. In this embodiment, the blades 14 and 15
Only the shape of the opening forming edge is different from that of the first embodiment, and the other configuration is the same. Therefore, the same members and portions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

First, a configuration different from the first embodiment will be described. The blades 14 and 15 in the present embodiment are arranged such that the second bending points 14e and 1
By providing 5e, the third edges 14f, 15f are formed within a range in which the opening 2a is opened and closed. The third edge portions 14f and 15f are connected to the third edge portion 14f with respect to the rotation angle of the drive pin 4b during the opening / closing operation.
And the third edge 15f intersect with each other, the change rate Δθ ₃ of the intersection angle formed by the intersection between the first edge 14b and the first edge 14b.
A relationship (Δθ ₃ > Δθ ₁ ) that is greater than the rate of change Δθ _{1 of the} intersection angle formed by the intersections of b.
It is formed to become. Therefore, at the time of the closing operation, the opening 2a is moved from the third edge 14f, 15f to the first edge 1f.
4b, 15b and then the second edges 14c, 15c
Thus, the doors are sequentially closed and closed.

Therefore, the opening 2a is provided at the first bending point 14
d and 15d are closed by the blades 14 and 15 immediately after passing through the opening 2a which is the exposure opening edge. In the initial stage, the first edges 14b and 15b and the second edge are closed.
In addition to the edges 14c, 15c, the third edges 14f, 15f
After that, at the end stage of the closing operation, the second edge portions 14c and 15c are rapidly closed by the relationship Δθ ₁ > Δθ ₂ as described in the first embodiment. And even in the case of this embodiment,
The timing to start closing the opening 2a is the first bending point 14
Immediately after d and 15d have passed through the opening 2a, and since the relationship of Δθ ₁ > Δθ ₂ is maintained, the operation time from the start of closing the opening 2a to the end of closing is shortened, and the shutter speed is reduced. Will be speeded up. Further, at the time of the opening operation, the blades 14 and 15 operate in the opposite direction to the above-described closing operation. In this case, the shutter speed can be increased as in the first embodiment. Things.

In this embodiment, the second bending points 14e and 15e are provided between the first bending points 14d and 15d of the blades 14 and 15 and the shaft support side, but the present invention is limited to such a shape. Without being performed, the first bending point 14d, 1
The opening forming edge may be formed so as to increase the number of bending points from 5d to the shaft support side. And
When the number of the bending points is further increased, the shape of the opening forming edge from the first bending points 14d, 15d to the shaft support side includes a large number of bending points and a large number of minute edges therebetween. In this case, the shutter speed can be increased in any case.

As described above, in the first embodiment and the second embodiment, the blades 14, 15 intersect sequentially from the pivot side to the tip side during the closing operation, so that the first edge portion 14b is provided. , 15b and second edges 14c, 15c and third edge 1
4f and 15f are the crossing angle change rates Δθ ₁ and Δθ, respectively.
₂ and Δθ ₃ are formed so as not to be “0”. Therefore, the closing operation is performed at high speed without collision between the pair of blades. However, if the flatness of the blades 14 and 15 can be obtained with high accuracy, the second edge portion 1 is set so that the change rate Δθ ₂ becomes “0”.
4c and 15c, and at the end stage of the closing operation,
The openings 2a may be closed in a parallel state instead of intersecting the second edges 14c and 15c.

In the first embodiment and the second embodiment,
The timing at which the energization of the coil 12 of the motor 3 is cut off is such that the drive pin 4b is brought into contact with the end face of the long groove 2b and the energization is cut off immediately after the opening and closing operation of the blade is completed. Depending on the situation, the coil 12 may be energized for a while immediately after the end of the opening / closing operation, or another well-known bounce prevention measure such as providing a buffer member may be employed. .

Further, in the first and second embodiments, the moving magnet type motor is used as the blade driving source. However, a stepping motor may be used instead.

[0044]

As described above, according to the blade of the camera shutter according to the present invention, at least one opening edge of each of the two blades that intersect sequentially from the pivot side to the tip side. The inflection point is provided to form edges that approach each other in the closing operation direction from the inflection point to the tip side, so that the shutter speed can be reduced with a simple configuration while maintaining the downsizing of the shutter and the power consumption. Can be speeded up. In particular, in the case of a digital camera using an image pickup device without a shutter function, even when the exposure aperture is enlarged, the shutter speed during the closing operation can be increased, and the shutter blades Since the effect of the bounce can be suppressed, it is more advantageous in controlling the exposure amount accurately.

[Brief description of the drawings]

FIG. 1 is a plan view of a first embodiment showing an initial state viewed from a subject side, showing a state in which a blade is opened.

FIG. 2 is a cross-sectional view of the first embodiment showing an overlapping relationship of main members.

FIG. 3 is a plan view of the first embodiment in the blade chamber showing both the prior art and the present invention blades for illustration, wherein the blade edge reaches the exposure opening edge during the closing operation; The state at the time of performing is shown.

FIG. 4 is a view showing a first example in the blade chamber shown in FIG.
FIG. 4 is a plan view of the embodiment, showing an initial stage in which the closing operation has progressed more than the state of FIG. 3.

FIG. 5 is a view showing a first example in the blade chamber shown in FIG.
FIG. 5 is a plan view of the embodiment, showing a state of an end stage in which the closing operation further proceeds after the state of FIG. 4.

FIG. 6 is a plan view of the first embodiment shown in the same manner as FIG. 1 and shows a state immediately after the closing operation is completed.

FIG. 7 is a timing chart of the first embodiment showing exposure characteristics of both the conventional art and the present invention.

FIG. 8 shows a state of an initial stage during the closing operation in the blade chamber of the second embodiment shown corresponding to FIG. 4 of the first embodiment.

[Explanation of symbols]

Reference Signs List 1 base plate 2 auxiliary base plate 1a, 2a opening 2b long groove 3 motor 4 rotor 4a rotating shaft 4b drive pin 5 upper frame 6 lower frame 1b, 6a, 14a, 15a, 16a, 17a long hole 7 yoke 8, 9, 10, DESCRIPTION OF SYMBOLS 11 Iron pin (holding means) 12 Coil 13, 13 Screw 14, 15 Blade (this invention) 14b, 15b 1st edge part (this invention) 14c, 15c 2nd edge part 14d, 15d 1st bending point 14e, 15e 2 bending point 14f, 15f Third edge 16, 17 Blade (prior art) 16b, 17b First edge (prior art) Δθ ₁ , Δθ ₂ , Δθ ₃ Rate of change of intersection angle + optical axis

Claims (3)

[Claims] 1. A base plate having an opening, and one end side is rotatably pivotally mounted at a lateral position of the opening, and the opening forming edges of each are directed from the pivot side to the tip side. And a motor for driving the blades, the opening forming edges of the two blades having at least one bending point. Wherein the opening forming edges are respectively formed so as to approach each other in the closing operation direction from the bending point toward the tip end side of the blade. 2. The method according to claim 1, wherein the rate of change of the intersection angle formed by the opening forming edges of the two blades is reduced immediately after passing the bending point during the closing operation. 2. A linear edge portion is formed from a point toward the tip of the blade.
7. The blade of the camera shutter according to item 1. 3. The opening according to claim 1, wherein the opening is circular, and the bending point on the most distal side coincides with a contact point of a tangent to the opening passing through the center of rotation of each of the blades. 1
Or the blade of the camera shutter according to 2.