JPS63157134A - Diaphragm mechanism - Google Patents

Abstract

PURPOSE:To reduce the interference of each blade as a whole, and to decrease a frictional load by moving only a part of diaphragm blades from the minimum diaphragm aperture position to a totally enclosed state position. CONSTITUTION:A vane 7 is turned in the stopped-down direction by fitting driving pins 4a-4f of each diaphragm blade 1a-1f into each cam groove hole 8a-8f of the vane 7, and when the vane 7 is turned in the stopped-down direction from the minimum diaphragm aperture position, the blade 1a is moved to a position for closing fully the diaphragm aperture. In this case, the driving pins 4b-4f float only in a connected and provided cam groove hole 80 and the blades 1b-1f remain standing still in the minimum diaphragm aperture position. Accordingly, a frictional load is decreased extremely.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an aperture mechanism, and more particularly, to an aperture mechanism used in cameras, etc., which is a lens shutter type aperture mechanism consisting of a plurality of sector blades. be.

[Prior art] In order to make the aperture aperture shape close to an ideal circle,
Multiple sector blades (aperture blades) formed to have the same shape and size
An aperture mechanism, also called an iris, that drives the iris circularly symmetrically with a arrow wheel is well known.

That is, as shown in FIG. 5, this aperture mechanism connects the bases of a plurality of aperture blades 1a to 1f formed in the same shape to support bins 3a to 3f fixedly planted at equal intervals on a retaining ring 2. Driving pins 4a to 4f, which are rotatably connected to each other and installed on each blade 1a to 1f, are inserted into cam slots 6a to 6f of the arrow wheel 5 rotatably fitted in the retaining ring 2. It is constructed by fitting the blades into each other and overlapping the free ends of the blades 1a to 1f with each other. As shown in FIG. 6, the arrow wheel 5 is a donut-shaped ring having a circular opening 5a in the center corresponding to the aperture diameter of the open aperture, and the blades 1a to 1f are mounted at equal intervals on support bins 3a.
Inclined cam slots 6a-6 for swinging around ~3f
By rotating this arrow wheel 5 by a driving member (not shown), the diameter of the aperture opening formed by the aperture blades 1a to 1f is changed.

The aperture mechanism that uses this arrow wheel to simultaneously drive multiple aperture blades of the same shape is a simple one in which the rotation amount of the arrow wheel and the change in the aperture aperture area (proportional to the change in F No.) are not linear. Alternatively, the shape of the cam slot formed in the aperture blade can be adjusted to change the rotation amount of the arrow wheel and the aperture opening area (FN
There are known devices in which the value (proportional to the change in o) is linear.

By the way, when using an aperture mechanism with such a configuration for temporary light shielding that also functions as a shutter, the conventional mechanism of this type requires that each aperture blade move only up to the minimum aperture diameter position. Because it is configured
It is not possible to obtain a fully open state that completely blocks light.

However, it is easy to imagine that in order to obtain a fully open state, the cam slot etc. in the conventional aperture mechanism can be extended and the aperture opening diameter made infinitely small. .

Furthermore, such a diaphragm mechanism is actually seen in simple diaphragms in video cameras and the like.

[Problems to be solved by the invention]However, in this type of diaphragm mechanism, the blades are assembled one after the other on top of the adjacent blades, and all the blades are sandwiched between the blades on both sides. The blade itself is thick, so the smaller the aperture diameter, the more the blade is affected by the thickness of other blades, creating bending stress in each blade. However, the frictional load between the blades increases.

Therefore, if you try to fully open the arrow wheel,
There is a problem that a large torque is required.

Also, the fanning of the blades is thick (there is a risk of damaging the blades themselves).

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems and provide an aperture mechanism that can easily be fully opened and can also be used as a light shielding shutter.

[Means and Construction for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides an aperture mechanism that drives a plurality of aperture blades to change the aperture aperture diameter. The present invention is characterized by providing means for further narrowing down some of the plurality of aperture blades after the aperture is moved to the minimum aperture position.

[Example] The present invention will be explained below with reference to illustrated embodiments.

Figure 1.2 shows an embodiment of the present invention,
In this embodiment, the present invention is applied to a diaphragm mechanism in which a driving pin, which is equivalent to a blade, is driven by a cam slot formed in a arrow wheel to open and close each blade.

Note that in this embodiment, a plurality of aperture blades 1a to 1f
, the retaining ring 2, etc. are exactly the same as the conventional aperture mechanism shown in FIG. 5, so a description thereof will be omitted, the same members will be given the same reference numerals, and only the differences will be explained.

In this embodiment, as shown in FIG.
Different from f. That is, the arrow wheel 7 is formed in a donut shape and has a circular lower part a corresponding to the open aperture diameter in the center.
The slanted cam slots 8a to 8f drilled in - are formed by the conventional slanted cam slots from the maximum diaphragm opening position to the minimum diaphragm opening position, and the cam grooves continuous thereto. A hole is connected to each inclined cam slot 8a-8f.

Among these consecutive cam slots, one cam slot, for example, the cam slot 8m that is connected to the cam slot 8a, when the arrow wheel 7 is rotated, the aperture blade 1a is further opened from the minimum aperture position. The other continuous cam slot 8o is formed in the shape of an operating cam that narrows the aperture to a fully closed position, and the other continuous cam slot 8o is along the same circumference 9 that does not move the aperture blades 1b-1f from the minimum aperture position even if the arrow wheel 7 is further rotated. It is formed in the shape of a partially arcuate floating cam.

If the drive pins 4a to 4f of the aperture blades 1a to 1f are fitted into the cam slots 8a to 8f of the arrow wheel 7 formed in this way and the arrow wheel 7 is rotated in the narrowing direction, the aperture can reach the minimum aperture opening position. It works like a conventional one. Then, when the arrow wheel 7 is further rotated in the narrowing direction from this minimum diaphragm opening position, the cam slot 8m moves the diaphragm blades 1a to a position where the diaphragm opening is completely closed. At this time, the other aperture blades 1b to 1f move through the drive pins 4b to 4f within the continuous cam full hole 8o.
Since it only moves freely, it remains stationary at the minimum aperture position.

Therefore, since only one aperture blade 1a moves to the fully closed position, the frictional load is greatly reduced.

Figure 3.4 shows another embodiment of the invention.

In this embodiment, the present invention is applied to an aperture mechanism in which a driving pin, which is equivalent to a arrow wheel, is fitted into a cam slot drilled in each aperture blade, and each blade is opened and closed by rotation of the arrow wheel. be.

In this embodiment, continuous cam grooves are provided for the cam slots 12a to 12f, which are bored in each of the aperture blades 11a to iff, for moving each blade from the maximum aperture opening position to the minimum aperture opening position. A hole is provided. Among these consecutive cam slots, one cam slot, for example, the third cam slot.
The cam groove hole 12m connected to the aperture blade 11a shown in the figure operates to narrow down the aperture blade 11a from the minimum aperture position 11aA shown by the two-dot chain line to the position 11aB shown by the dotted line where the aperture opening is fully closed when the arrow wheel is rotated. Formed in a cam shape. As shown in FIG. 4, the other continuous cam slots 12° are provided with drive pins that do not move the aperture blades 11b to llf from the minimum aperture positions 11bA to 11fA indicated by the two-dot chain lines even if the arrow wheel is further rotated. It is formed into a partially arcuate floating cam shape along the movement circumferential locus 14 of 13b to 13f.

In this embodiment configured in this way, by inserting the drive pins 13a to 13f of the arrow wheel into the cam slots 12a to 12f of each blade 11a to llf and rotating the arrow wheel in the narrowing direction, the minimum aperture can be achieved. Opening positions 11aA to 11f
Up to A, the cam slots 12a to 12f operate in the same manner as the conventional one. Then, when the arrow wheel is further rotated in the narrowing direction from this minimum aperture opening position, the cam slot 12m causes only the aperture blades 11a to fully close the aperture opening to a position 11a.
Move to B. At this time, the other aperture blades 11b to 11l
lf is the driving pin 13b to 13 inside the continuous cam slot 12o.
f only moves freely, and is held stationary at the minimum diaphragm aperture position.

In this way, in this embodiment as well, the fully open state can be obtained by moving only one blade 11a.

In addition, in each of the above embodiments, only one blade was moved, but instead of making the operating cam shape the same for all blades, it is possible to make some blades different from other blades. Of course, it is not limited to just one blade.

[Effects of the Invention] As described above, according to the present invention, when the aperture mechanism of this type is operated to the fully open state and used for a light shielding mechanism such as a shutter, only some of the aperture blades are moved from the minimum aperture aperture position to the fully open state. Since the blades are moved to different positions, the interference between the blades as a whole is reduced, the frictional load is reduced, and the driving torque can be reduced, which is a remarkable effect.

In addition, a fully open state can be achieved without any hindrance to the diaphragm operation from the open position to the minimum diaphragm opening position.

[Brief explanation of the drawing]

Fig. 1 is a front view of an aperture mechanism showing one embodiment of the present invention, Fig. 2 is a front view showing only the arrow wheel of the aperture mechanism shown in Fig. 1 above, and Figs. Each front view of the aperture blades in an aperture mechanism showing another embodiment of the invention, FIG. 5 is a front view of a conventional aperture mechanism, and FIG. 6 is a front view showing only the arrow wheel taken out from FIG. It is a diagram.

Claims (1)

[Claims] In an aperture mechanism that changes the aperture diameter by driving a plurality of aperture blades, after the plurality of aperture blades are moved to the minimum aperture position, one of the aperture blades is moved to a minimum aperture position. A diaphragm mechanism characterized by having a means for further narrowing down a part.