JPS62111241A - Shutter device used as electromagnetically driven diaphragm in common - Google Patents

Abstract

PURPOSE:To obtain a device having the open/close characteristic which approximates an ideal characteristic very much, by providing an inertia ring independently of an open/close ring and turning the inertia ring to interlock the inertia ring and an open/ close plate with each other so that the inertia ring is rotated integrally only for turning in the shutter opening direction. CONSTITUTION:When a current is not applied to a coil 22, an inertia ring 16 is turned on the direction of an arrow (a) by the force of a tension spring 29 and an interlocking pin 24 is clipped between a notch 26 and the end part of a turning range control aperture 25. At this time, a shutter aperture formed with shutter blades is closed. When a current is applied in the shutter opening direction in this state, the shutter aperture formed with shutter blades is opened by the electromagnetic action of a magnet 23. When an open/close plate 15 is turned in the shutter opening direction, the interlocking pin 24 pushes the end part 26a of the notch 26 to turn the inertia ring 16 together. Consequently, since the inertia ring 16 is turned together by the turning energy of the open/close plate 15, the opening speed of the shutter is made lower and is set freely by setting the mass of the inertia ring 16 and the force of the tension spring 29.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to an improvement in an aperture and shutter device for cameras, usually called a program shutter, which is driven by electromagnetic force.

"Prior art and its problems" This type of programmable shutter, as shown in Figure 3,
The basic operation is that the shutter blade is normally closed, and at an appropriate time during the opening of the shutter blade, the direction of operation of the shutter blade is reversed and the shutter blade is closed again. Figures (a) and (b) show the cases of relative short-time exposure and long-time exposure, and the aperture area (corresponding to the F number) changes with the shutter speed depending on the length of the exposure time. .

By the way, in this program shutter, the opening speed when the shutter opens needs to be set so as not to be too fast. If the aperture speed is too fast, the time required to obtain a proper exposure time is too short, and exposure errors are likely to occur, because even a slight shift in the inversion start time can greatly change the aperture area. For this reason, in the case of a conventional diaphragm/shutter device mainly based on a mechanical structure, a governor is generally used to optimize the aperture speed.

On the other hand, as a device for electromagnetically driving the shutter blade to open and close, there is a device in which a coil is installed on the opening/closing plate that opens and closes the shutter blade, and the opening/closing ring is rotated by electromagnetic force (for example, Japanese Patent Application No. 130829/1989). In this electromagnetic program shutter, the opening/closing ring is biased in the closing direction by a weak spring means, thereby weakening the rotational force in the opening direction due to electromagnetic force, and increasing the speed in the opening direction compared to that in the closing direction. Efforts are being made to make it smaller. However, in this type of shutter device, the mass of movable parts including the shutter blades and opening/closing plate is extremely small, so setting the force relationship between the spring biasing force and the electromagnetic force is delicate and difficult, and the setting is likely to be incorrect. It was difficult to obtain a suitable speed (exposure).

Furthermore, if the mass of a movable object such as an opening/closing plate is increased in order to slow down the speed in the opening direction, the inertial mass of the movable object will increase, and even if the drive current is reversed, the amount of overshoot will increase as shown by the broken line in Figure 4. becomes a cause of exposure error. Ideally, as shown by the solid line in the same figure, when the drive current is reversed in the closing direction, it would be good to close immediately.

"Purpose of invention" The present invention has ideal switching characteristics shown by the solid line in FIG.

Another object of the present invention is to obtain an electromagnetically driven diaphragm/shutter device having opening/closing characteristics extremely similar to this.

"Summary of the Invention" The present invention provides for the rotation of the opening/closing plate in the shutter opening direction.
This was done based on the idea of providing a certain amount of mechanical resistance while eliminating this resistance when the shutter rotates in the closing direction. It is characterized in that the inertia ring is biased to rotate in the shutter closing direction, and the inertia ring and the opening/closing plate are interlocked so that the inertia ring rotates integrally only in response to the rotation of the opening/closing plate in the shutter opening direction.

"Embodiments of the Invention" The present invention will be described below with reference to illustrated embodiments. FIG. 1 shows the mechanical structure of the shutter device of the present invention, in which a substrate 11
A circular opening 12 centered on the optical axis 0 is bored in the opening 12 , and an annular support part 13 .
14 is formed. An annular opening/closing plate 15 and an inertia ring 16 are rotatably supported on the annular support parts 13 and 14, respectively.

A pair of opening/closing pins 17 are implanted in the opening/closing plate 15, and the opening/closing pins 17 are fitted into drive holes 19 of a pair of shutter blades 18 which also serve as an aperture (hereinafter simply referred to as shutter blades). The shutter blade 18 is rotatable around a fixed pin 21 fitted into a support hole 20 on the outside thereof, and when the opening/closing plate 15 is rotated in the direction of arrow a, the shutter opening (diaphragm) formed by the pair of shutter blades 18 is opened. opening) is closed, and the opposite b
Opens when rotated in the direction.

A coil 22 and a magnet 23 are fixed to the opening/closing plate 15 and the substrate 11, respectively, as means for electromagnetically rotating the opening/closing plate 15. As is well known, in this electromagnetic driving means, when a driving current in the opening direction is applied to the coil 22, the opening/closing plate 15 is moved by an electromagnetic force acting between it and the magnet 23.
When the opening/closing plate 15 rotates in the a direction and a closing direction current opposite to the opening direction current is passed through the coil 22, the opening/closing plate 15 rotates in the a direction.

The opening/closing plate 15 also has an inertia ring 1 facing toward the board ll side.
A link bottle 24 with 6 is installed.

This interlocking bin 24 has a rotation range regulating opening 25 in the board 11.
and extends into the notch 26 of the inertia ring 16 .

The inertia ring 16 is moved in the direction of arrow a, that is, the opening/closing plate 15, by means of a weak tension spring 29 stretched between a pin 27 for a spring hook attached to the inertia ring 16 and a pin 28 for a spring hook attached to the base plate 11. It is biased in the closing direction. This tension spring 2
9 is a weak spring sufficient to rotate the inertia ring 16 by itself. Therefore, the interlocking bin 24 has one end 25a of the rotation range regulating opening 25 and one end 25a of the notch 26.
6a, and at this time, the shutter opening by the shutter blade 18 is closed.The circumferential length of the zero rotation range regulating opening 25 is the length from when the shutter opening is fully closed to fully opened by the shutter blade 18. The length L in the circumferential direction of the notch 26 is set to a size that covers the shutter when the opening/closing plate 15 is rotated in the shutter opening direction and then reversed to the closing direction. It is set so as not to come into contact with the other end 26b.

Therefore, in the present device having the above configuration, when no current is applied to the coil 22, the force of the tension spring 29 causes the inertia ring to
6 rotates in the direction of arrow a, and the interlocking pin 24 is sandwiched between the notch 26 and the end of the rotation range regulating opening 25 (see Fig. 2).
a)) At this time, the opening/closing plate 15 is also located at the end of rotation in the direction a, and the shutter opening by the shutter blade 18 is closed. When a current is applied to the coil 22 in the shutter opening direction from this state, the opening/closing plate 1
5 rotates in the direction indicated by the arrow, and the shutter opening by the shutter blade 18 opens due to the relationship between the opening/closing pin 17 and the drive hole 19. When the opening/closing plate 15 rotates in the shutter opening direction, the interlocking pin 24 opens the notch 26. Push the end 26a of the inertia ring 16 to rotate it together. Therefore, the opening/closing plate 15
When the opening/closing plate 15 rotates in the opening direction, the inertia ring 16 is also rotated by the rotational energy of the opening/closing plate 15, so the rotational speed of the opening/closing plate 15, that is, the opening speed of the shutter becomes slow. This opening speed (the slope shown by the solid line in FIG. 4) can be freely set by setting the mass of the inertia ring 16 and the force of the tension spring 29.

Next, when the direction of the drive current flowing through the coil 22 is reversed and a closing direction current is passed, the opening/closing plate 15 and the shutter blade 18 immediately reverse their rotational direction due to their small mass.
Figure (b)), the shutter is closed. At this time, the interlocking bin 24 of the opening/closing plate 15 moves within the notch 26. On the other hand,
Due to its inertial force, the inertia ring 16 does not immediately change direction even if the drive current of the coil 22 is reversed, and the opening/closing plate 1
Change direction later than 5. The force of the tension spring 29 is not strong enough to immediately cancel out the inertial rotational force of the inertia ring 16.

The inertia ring 16 then returns to its original position by the force of the tension spring 29, and the end 26a of the notch 26 and the rotation range regulating opening 2
The state returns to the initial state in which the interlocking bin 24 is sandwiched between the end portion 25a of the holder 5 and the end portion 25a of the interlocking bin 24.

The present invention has been described above assuming that a current is passed through the coil 22 in both the shutter opening direction and the shutter closing direction. 22 may be configured to allow current to flow only in the shutter opening direction. In this case, since it is sufficient to flow current in only one direction through the coil 22, it is possible to simplify the configuration of the drive circuit. However, even when the opening/closing plate 15 is biased in the shutter closing direction by a spring, it is also possible to configure the coil 22 to flow a current in the shutter closing direction.

"Effects of the Invention" As described above, in the present invention, when the shutter blade opens, the inertia ring is rotated by the opening/closing plate, so the shutter opening speed can be appropriately slowed down by the inertia of the inertia ring. On the other hand, when the shutter blade closes, only the opening/closing plate rotates, so the shutter opening can be quickly closed and more ideal opening/closing characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the electromagnetically driven aperture and shutter device of the present invention, FIGS. 2(a) and (b) are front views of essential parts showing different operating states of the device of the present invention, and FIG. Figure, 4th
The figure is a graph showing the operating characteristics of the program shutter. DESCRIPTION OF SYMBOLS 11... Board, 15... Opening/closing plate, 16... Inertia ring, 17... Opening/closing pin, 18... Shutter blade serving as aperture, 19... Drive hole, 22... Coil, 23・
...Magnet, 24...Interlocking pin, 25...Rotation range regulating opening, 26...Notch, 27.28...Spring hook is pin, 29...Tension spring. Patent applicant Asahi Optical Industry Co., Ltd. Agent Kunio Miura Shigeru Matsui Figure 1 (a) (b) Figure 112 Time Figure 3 Procedures Amendment February-3, 1986 Application No. 60-251553 10 Name of the invention Electromagnetic drive diaphragm/shutter device 3, person making the amendment Relationship to the case Patent applicant address 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Address: 174 Telephone: 03-960- 5162 q, "Detailed Description of the Invention" column J of the specification to be amended, page 2, line 17 to line 20 of the "Detailed Description of the Invention" column of the statement of contents of the amendment [For this reason, conventional... was common. ' shall be amended as follows. Also, in a camera using this type of programmed shutter, when performing so-called flashmatic photography, that is, when firing the flash at the time when the shutter reaches the appropriate F value during opening, the opening speed is too fast. Therefore, even a slight difference in the flash firing time could cause a large exposure error. For this reason, in the case of a conventional program shutter mainly based on a mechanical structure, a governor is generally used to optimize the opening speed, resulting in a complicated structure.

Claims (1)

[Claims] (1) In an electromagnetically driven diaphragm/shutter device that includes an opening/closing plate that opens and closes the diaphragm/shutter blade as it rotates, and an electromagnetic drive means that rotates the opening/closing plate using electromagnetic force,
Further, the inertia ring is rotatably provided, and a weak spring means is provided to bias the inertia ring to rotate in the same direction as the shutter closing direction of the opening/closing plate, and the inertia ring and the opening/closing plate are connected to each other by the opening/closing plate. An electromagnetically driven aperture shutter device characterized in that an inertia ring is interlocked to rotate against the spring means only when the shutter is rotated in the shutter opening direction.