JPH1096974A - Camera shutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera shutter which is constituted so as to excellently obtain an opening operation characteristic and be suitable for miniaturization. SOLUTION: In a ring-like linking member 2, slots 2f, 2g and 2h are fitted on the shafts 1i, 1j and 1k of a shutter base plate 1 and extended parts 2c, 2d and 2e are placed on receiving parts 1f, 1g and 1h. Shutter blades 3, 4 and 5 are rotatably attached to the shafts 1i, 1j and 1k and further, the linking member 2 by connecting shafts 6, 7 and 8. The linking member 2 is energized upward by a spring 13, for allowing the shutter blades 3, 4 and 5 to execute opening operations. Further, the pin 12a of an actuating member 12 actuated by a moving magnet type motor pushes a recessed part 2a, to actuate the linking member 2 downward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shutter in which a plurality of shutter blades open and close a circular exposure opening by a reciprocating operation during a film exposure operation.

[0002]

2. Description of the Related Art A shutter of this type is called a lens shutter. When an exposure operation is performed, a shutter blade opens an exposure opening from an optical axis center.
After that, it is closed toward the center of the optical axis. During the operation, it is ideal that the plurality of shutter blades can always maintain a substantially circular opening shape. Therefore, in the past, a plurality of shutter blades were arranged at equal intervals around the exposure opening, and they were operated by a drive ring that reciprocates around the optical axis. In addition, the rotation of the drive ring is performed only by the spring force. However, in such a shutter, since the drive ring is disposed in a groove formed substantially over the entire circumference with respect to the shutter base plate surface, an extremely large peripheral surface frictional resistance is generated regardless of the plane frictional resistance. There was naturally a limit to speeding up.

[0003] After that, with the advancement of film technology and lens technology, the above-mentioned opening shape during operation has been allowed to be somewhat broken, and the cost reduction has been emphasized. It has become. for that reason,
Those using a drive ring disappear except for a professional large shutter, and instead reciprocate relatively.
Single-blade shutters have become mainstream. However,
Since the opening shape during the operation described above cannot be largely destroyed, it is designed to obtain a shape that is a little closer to the ideal as far as possible as a two-blade shutter, and the shape of each blade is It was decided along. However, recently, not only cost reduction,
The demand for miniaturization and electrification has increased, especially for IX.
With the advent of the 240 cartridge film (Advanced Photo System Film), the demand for miniaturization has become extremely large.

When the size of the lens shutter is reduced, it is important how the space for accommodating the shutter blades when the exposure opening is fully opened can be reduced. However, in the two-bladed shutter described above, downsizing has already been performed to the extent possible so far. To further reduce the size, the shape of the blades must be changed. The opening shape cannot be maintained during operation. Therefore, in order to further reduce the size, it is absolutely necessary to use three or more shutter blades. However, for the above-described reasons, it is not possible to use a conventional drive ring. Accordingly, the applicant proposed a shutter in which an actuating member referred to as a link member that does not generate peripheral frictional resistance is provided, and three or more shutter blades are connected to the shutter to open and close the exposure opening. It is known from Japanese Utility Model Laid-Open No. 7-5131, Japanese Patent Laid-Open No. 7-13218, and the like.

On the other hand, in recent lens shutters, motors have been increasingly used as driving sources in accordance with the above-mentioned demand for electric motors, from the viewpoint that it is not necessary to set a shutter driving mechanism for each photographing. In the early days, pulse motors were often used. However, although a pulse motor can provide a large driving force, there is a problem that downsizing is not easy and the cost is high. Therefore, attention has been paid to the use of a motor called a moving magnet type motor, which can cope with downsizing at a lower cost than a pulse motor. This motor is characterized in that the rotor of the permanent magnet is reciprocated within a predetermined angle range depending on the direction of energization of the coil, and among the shutters described in the above two publications, Japanese Patent Laid-Open No. 7-13218. The moving magnet type motor is used for the shutter described in the publication. The present invention relates to a camera shutter in which a link member connecting three or more shutter blades is operated by a moving magnet type motor.

[0006]

By the way, as described above, the moving magnet type motor has a feature that it is inexpensive and easy to be miniaturized, but is inferior in the startability as compared with the pulse motor, The time required from the start of energization until the predetermined driving force is obtained is long,
In addition, there is a problem that the driving force is easily influenced by a slight variation in load. Further, there is a problem that the driving force is easily affected by a change in voltage (not necessarily a change in battery voltage).

[0007] Therefore, when a link member connecting three or more shutter blades is operated by a moving magnet type motor, such as a shutter targeted by the present invention, a normal shutter, for example, a two-bladed shutter blade is used. The load becomes much larger than that directly operated by a moving magnet type motor.Therefore, various problems that must be dealt with seriously cannot be considered relatively easy as before. I do. That is, first, there is a problem that it is difficult to increase the speed. Also, the rising characteristics of individual shutters (the operating characteristics of the shutter blades from pinhole to fully open)
However, there is a problem that the dispersion of the data becomes large and the adjustment becomes difficult. In particular, if the adjustment is performed only by changing the operation start position of the shutter blade, a large adjustment space is required, so that the demand for downsizing cannot be met. In addition, there is a problem that even when photographing is performed under a constant photographing condition, the exposure result is largely different due to a change in voltage (cutting unevenness cannot be ignored). Further, there is a problem that the exposure result greatly differs depending on how the camera is held (a posture difference cannot be ignored).

[0008] The present invention has been made to solve such a problem.
An object of the present invention is to provide a camera shutter suitable for downsizing, in which a link member connecting at least two shutter blades can be stably operated by a moving magnet type motor.

[0009]

In order to achieve the above-mentioned object, a camera shutter according to the present invention is arranged in a blade chamber between a shutter base plate and an auxiliary base plate, and a fulcrum and a moving point are provided at predetermined intervals. And three or more shutter blades that open and close the exposure opening by reciprocatingly rotating at the fulcrum around the circular opening around the optical axis. Or, it is arc-shaped and is disposed so as to surround the exposure opening in the blade chamber, is rotatably connected to a moving point of each of the shutter blades, and reciprocates in a direction crossing the optical axis. A link member for reciprocatingly rotating each of the shutter blades at each fulcrum, a spring for urging the link member so that the shutter blades operate in a direction to open the exposure opening, And a moving magnet type motor reciprocates in an angular range, so that an actuating member for actuating against the link member to the biasing force of the spring by one operation of the motor.

In the camera shutter according to the present invention, preferably, the spring causes an end face of the link member to be brought into contact with the operating member by its urging force. In the camera shutter of the present invention, preferably, a pin is provided on one of the link member and the operating member, and a slot is provided on the other,
Both are connected by pin and slot. Further, in the camera shutter of the present invention, preferably, the spring is mounted outside the blade chamber, and its working end is inserted into the blade chamber from a window formed in the shutter base plate or the auxiliary base plate. The window is provided with a light blocking portion so as not to affect the action of the spring.

[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 of the blade chamber with the auxiliary base plate removed, showing a shutter closed state. FIG. 2 is a rear view of FIG. 1, but does not show the shutter blades that should be seen from the exposure opening. FIG. 3 is a partial cross-sectional view of FIG.
The cross section is shown in an expanded state. FIG. 4 is a plan view viewed in the same manner as FIG. 1, and shows a fully opened state of the shutter.

First, the configuration of this embodiment will be described. FIG.
1, the shutter base plate 1 is made of a synthetic resin and has a circular opening 1a centered on the optical axis. On the outer peripheral edge of the shutter base plate 1, a wall 1b projecting toward the near side is formed, and screw holes 1c that do not penetrate are formed at three places. In addition, an auxiliary base plate made of a synthetic resin (not shown) is disposed in front of the shutter base plate 1.
It is attached to the hole 1c by a screw. Two projections are formed on this auxiliary base plate, and these are formed by inserting holes 1d and 1e formed in the shutter base plate 1 through the holes.
Is fitted. Further, a circular opening centered on the optical axis is also formed in the auxiliary base plate, but since the diameter is larger than the opening 1a, the opening for exposure as a shutter is regulated by the opening 1a. In this embodiment, the blade chamber is thus formed between the shutter base plate 1 and the auxiliary base plate, and is shielded by the wall 1b so that light from the outer peripheral direction does not enter.

An annular link member 2 is provided in the blade chamber.
And three shutter blades 3, 4, and 5, are arranged in the order of the link member 2, the shutter blade 3, the shutter blade 4, and the shutter blade 5 from the paper surface toward the near side. . In the assembled state, a part of the auxiliary base plate (not shown) pushes the shutter blades 5 lightly in the paper surface direction. First, the link member 2
Has a concave portion 2a, an engaging portion 2b, and three overhang portions 2c, 2
d, 2e, and three slots (long holes) 2f, 2g, 2h. And the overhang parts 2c, 2d, 2e
They are respectively mounted on shelf-like receiving portions 1f, 1g, and 1h formed in the shutter base plate 1 with a large thickness.
f, 2g, and 2h are fitted to shafts 1i, 1j, and 1k, respectively, erected on the shutter base plate 1.

The shutter blades 3, 4, and 5 are respectively
These holes are fitted to the shafts 1i, 1j, and 1k, and the opening and closing operation can be performed using the fitted portions as fulcrums. Further, each of the shutter blades 3, 4, 5 is connected to a connecting shaft 6,
It is attached to the link member 2 by 7 and 8. Each of the connecting shafts 6, 7, 8 is a rivet component, is inserted from the back side of the link member 2, and is caulked on the surface side of each of the shutter blades 3, 4, 5. Therefore, the space between the link member 2 and each of the connection shafts 6, 7, 8 is movable,
Reference numerals 7 and 8 are moving points of the shutter blades 3, 4, and 5, respectively. The shutter blade 5 has a protrusion 5a at its tip.
Are formed. This is to block the optical path of the photoreflector in the initial stage of the opening operation, but since the configuration and function of such a detection mechanism are well known, detailed description thereof will be omitted.

On the back side of the shutter base plate 1, a moving magnet type motor is mounted. Since this moving magnet type motor is well known, only the minimum members considered necessary for the description of the present embodiment are shown in FIG.
It is shown in As can be seen from FIG. 2, a motor frame 9 indicated by a dashed line is attached to the shutter base plate 1 by two screws 10, and forms a motor chamber between the motor base 9 and the shutter base plate 1. Although the stator is not shown, the rotor 11 is pivotally supported by the shutter base plate 1 and the motor frame 9, and an operating pin 12 a of an operating member 12 formed integrally therewith has a window formed in the shutter base plate 1. Part 1m
Can be penetrated to the blade chamber to engage with the end face of the concave portion 2a of the link member 2.

As can be seen from FIGS. 2 and 3, on the rear side of the shutter base plate 1, a shaft 1n around which a spring 13 is wound is provided.
Is erected. The shaft 1n, spring 13 is formed projection 1n ₁ is to prevent the coming off, also in order to form the projection 1n ₁ by molding, a hole 1p are formed on the shutter base plate 1 I have. Furthermore,
On the back side of the shutter base plate 1, a light shielding portion 1r is formed so as to cover a window 1q formed in the shutter base plate 1, and an axial spring hook 1s is formed. The spring 13 has one end hung on the spring hook 1s, the other end penetrating from the window 1q into the blade chamber, and being hung on the engaging portion 2b of the link member 2. Accordingly, in FIG. 1, the link member 2 is urged by the spring 13 to operate upward. In FIGS. 1 and 3, a stopper 1t is formed on the wall 1b to prevent the link member 2 from operating downward.

Next, the operation of this embodiment will be described. FIG. 1 shows the shutter in a closed state.
Is pressed against the end face of the concave portion 2a by the operating pin 12a,
It is operated downward against the spring 13 and its operation is stopped by the stopper 1t. When the shutter is released in this state, the power switch is first closed, and the photo reflector (not shown) attached to the auxiliary base plate is turned on. As a result, the light emitted from the light emitting section into the blade chamber is transmitted to the shutter base plate 1.
The light is reflected by a reflection sheet (not shown) attached to the light source, and enters the light receiving unit. After going through such preparations,
When the coil of the moving magnet type motor is energized in the forward direction, the rotor 11 rotates clockwise by a predetermined angle with the operating member 12 in FIG.

Thus, the operating member 12 is connected to the rotor 1
1, the operating pin 12a moves upward in FIG. As described above, in the case of the moving magnet type motor, this operation is initially slow and unstable, but in the case of this embodiment, the spring 13 biases the link member 2. Therefore, the link member 2 does not simply follow the operation of the operation pin 12a, but rather operates by the urging force of the spring 13
plays the role of pushing a positively. Therefore, the operating pin 12
In the case of “a”, the operation characteristics are better and the operation is more stable than when the motor is operated only by the motor. And
The upward movement of the link member 2 is performed by the shutter blades 3,
Since the distance between the fulcrum parts (positions of the axes 1i, 1j, 1k) and the moving point parts (positions of the connection axes 6, 7, 8) is invariable, the operation is performed in a circular arc. become.

As described above, when the link member 2 starts operating upward, the shutter blades 3, 4, and 5 also rotate the shafts 1i and 1i, respectively.
Rotation starts counterclockwise about 1j and 1k.
When the projection 5a of the shutter blade 5 interrupts the optical path of the photo reflector before the pinhole state is established, the output signal starts counting the time by the exposure time control circuit. After that, the shutter blades 3, 4, 5
The opening 1a is brought into a pinhole state, and the opening 1a is opened centering on the optical axis. After the opening 1a is fully opened, the opening 1a is stopped by contacting the wall 1b, and the fully opened state shown in FIG.
In the present embodiment, during the opening operation, the link member 2 slides in surface contact with the shutter base plate 1 only with respect to the receiving portions 1f, 1g, and 1h. The member 2 has extremely low frictional resistance and can be operated smoothly. However, the present invention is not limited to this configuration, and a minimum bearing surface may be provided on the shutter base plate 1 or the auxiliary base plate as necessary. It does not hinder.

Thereafter, when the exposure time control circuit completes a predetermined count in the fully opened state of FIG. 4, the coil of the moving magnet type motor is energized in the opposite direction to the above according to the output signal. As will be described later, the magnetic force of the permanent magnet is added to the resulting electromagnetic force, and the rotor 11 is rotated counterclockwise in FIG. Therefore, in FIG. 4, the operating pin 12 a pushes the end face of the concave portion 2 a and operates the link member 2 downward against the urging force of the spring 13. The operation of the link member 2 is performed in the same manner as in the above case, in which the overhang portions 2c, 2d, 2e and the receiving portions 1f, 1
The shutter blades 3, 4, and 5 are rotated clockwise about the shafts 1i, 1j, and 1k, respectively, by the sliding relationship with g and 1h. Then, after the shutter blades 3, 4, and 5 close the opening 1a, the link member 2 comes into contact with the stopper 1t and stops, and is in the state of FIG.

After the respective members return to the state shown in FIG. 1, the energization of the coil of the moving magnet type motor is cut off, and the film is wound up in preparation for the next photographing. Is made of a permanent magnet, so that even if the power supply to the coil is cut off, its rotational position is maintained and the opening 1a is kept closed. Although a method for doing so is well known, it is simply described that the equilibrium position of the rotor 11 in the non-energized state is set to a position further rotated counterclockwise than the rotation position shown in FIG. It is. Therefore, in FIG. 1, even in the non-energized state, the link member 2 is pushed downward by the magnetic action of the permanent magnet of the rotor 11. However,
Since the urging force of the spring 13 acts on such a magnetic action, if there is any concern about maintaining the closed state in terms of the balance between the two forces, the operating member 12 is operated by another member in the closed state. May be suppressed, and the inhibition may be canceled at the initial stage of the release for the next photographing.

As described above, according to the present embodiment, in opening the shutter, the link member 2 and the shutter blades 3, 4, and 5 do not become a load on the motor at all, but rather are hung on the link member 2. Since the spring 13 is pushed in the rotation direction by the urging force of the spring 13, the starting property, which is a weak point of the moving magnet type motor, is greatly improved,
The rising characteristics of 4 and 5 are improved and the variation is reduced. Therefore, the exposure control in the high-speed region of the shutter speed can be stably obtained, and the flash light emission control can be simplified.

In the above embodiment, the operating member 1
2 is engaged with the end face of the concave portion 2a of the link member 2, but instead of this configuration, a slot (a long hole) is formed in the link member 2 and the operating pin 12a is fitted therein. A so-called pin / slot connection may be used. In that case, a slot may be formed in the operation member 12 and a pin may be provided in the link member 2. However, in the case of such a pin-slot combination configuration, the link member 2 and the shutter blades 3, 4, and 5 become loads in the opening operation, and therefore are inferior to the configuration of the embodiment. However, a certain effect can be obtained as long as the spring 13 exists. Further, in the above embodiment, the operating member 12 is formed integrally with the rotor 11, but the operating member 12 is attached to the shutter base plate 1 and is reciprocated in conjunction with the rotation of the rotor 11. It does not matter.

In the above embodiment, the link member 2 has an annular shape, but the present invention is not limited to such a shape. For example, in the embodiment, the connecting portion to the shutter blade 3 and the connecting portion to the shutter blade 4 may be left, and the space between them may be omitted to form an arc.
In this case, the opening 1a has a shape that surrounds about 240 degrees. Further, in the above embodiment, three shutter blades are used.
More than one sheet is acceptable. If the number is four, the link member 2 may have a shape surrounding the opening 1a by about 270 degrees. However, this is the case where the shutter blades are arranged at equal intervals around the opening 1a, and even if three shutter blades are used, there is some sacrifice in size reduction. If
It is also possible to make the shape 240 degrees or less. In the shutter of the present invention, the link member 2 includes the above-described means in order to obtain a high shutter speed and to reduce the influence of the difference in the attitude of the camera at the time of shooting. It is necessary to reduce the weight as much as possible.

Further, in the above embodiment, the spring 13
Is attached to the shutter base plate 1 outside the blade chamber. However, the present invention is not particularly limited to such a configuration, and may be attached to the shutter base plate 1 or the auxiliary base plate inside the blade chamber. It may be attached to the auxiliary base plate outside the blade chamber. The same can be said for a moving magnet type motor.

[0026]

As described above, according to the present invention, in a camera shutter in which a link member connecting three or more shutter blades is operated by a moving magnet type motor, the link member is opened by a spring and actuated. Since the motor is biased in the direction, an extremely stable opening operation can be obtained even if a moving magnet type motor having difficulty in starting and being easily influenced by a change in voltage is used. This also facilitates the adjustment of the assembly of the individual shutters, and facilitates high-speed operation.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of the present invention, showing a shutter closed state.

FIG. 2 is a rear view of FIG. 1 in which illustration of a shutter blade is omitted.

FIG. 3 is a partial cross-sectional view of FIG.

FIG. 4 is a plan view of the embodiment as viewed in the same manner as in FIG. 1, showing a shutter fully opened state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shutter base plate 1a Opening 1b Wall 1c Screw hole 1d, 1e Hole 1f, 1g, 1h Receiving part 1i, 1j, 1k, 1n Axis 1m, 1q Window 1p Hole 1r Light shielding part 1s Spring hook 1t Stopper 2 Link member 2a Recess 2b engaging portion 2c, 2d, 2e overhanging portion 2f, 2g, 2h slot 3, 4, 5 shutter blade 5a projection 6, 7, 8 connecting shaft 9 motor frame 10 screw 11 rotor 12 operating member 12a operating pin 13 Spring

Claims (4)

[Claims] 1. An exposure opening, which is disposed in a blade chamber between a shutter base plate and an auxiliary base plate, has a fulcrum and a moving point at predetermined intervals, and has a circular shape around the optical axis. Three or more shutter blades that open and close the exposure opening by reciprocatingly rotating around the fulcrum around the fulcrum, and are arranged in an annular or arcuate shape so as to surround the exposure opening in the blade chamber. A link member rotatably connected to a moving point portion of each of the shutter blades and reciprocating in a direction crossing the optical axis to reciprocally rotate the shutter blades at respective fulcrum portions; A spring urging the link member so that the blades operate in a direction to open the exposure opening, a moving magnet type motor reciprocating in a predetermined angle range, and one of the motors An actuating member for actuating the link member by movement against the urging force of the spring. 2. The camera shutter according to claim 1, wherein the spring causes an end face of the link member to be brought into contact with the operating member by an urging force of the spring. 3. The camera shutter according to claim 1, wherein a pin is provided on one of the link member and the actuating member, and a slot is provided on the other, so that the pin and the slot are connected to each other. . 4. The spring is mounted outside the blade chamber, and its working end is inserted into the blade chamber from a window formed in the shutter base plate or the auxiliary base plate. 4. The camera shutter according to claim 1, wherein a light-shielding portion is provided so as not to affect an operation.