JPH02242239A - Diaphragm mechanism - Google Patents

Abstract

PURPOSE:To miniaturize an entire diaphragm mechanism by providing a 2nd stop blade group which shields light on a superposed part other than the effective diameter of a diaphragm separately from a 1st stop blade group which decides the effective diameter of the diaphragm. CONSTITUTION:The 2nd stop blade 6 arranged on the back surface side of a common swage block 5 is formed in a circular arc shape whose width is nearly constant and a fixed dowel 8 planted on one end side of the blade 6 is turnably fitted in the swage block 5. Moreover, a rotating dowel 9 planted on the blade 6 is fitted in the cam groove 7b of a windmill 7 where an aperture 7a is formed in the center so as to slide. By rotating the windmill 7 with an optical axis as a center against the swage block 5, the plural stop blades 6 are inclined with the fixed dowel 8 as a center so as to cover a dead space other than the effective diameter of the diaphragm which is formed between the stop blades 1 of the stop blade group for deciding the effective diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aperture mechanism for a camera lens.

[Prior Art] FIGS. 6 to 8 show the aperture mechanism of a conventional camera lens.

A rotating shaft 51 called a fixed dowel is installed on one side of each of the plurality of aperture blades 50, and a bottle 52 called a rotating dowel is installed on the other side, and the aperture blade container is called a honeycomb. (A circular opening 54 centered on the optical axis is provided) A plurality of aperture blades are formed by fitting each rotating shaft 51 into each shaft hole 55 of the same number as the aperture blades 50 drilled in 53. 50, and a cam member called a windmill (provided with a circular opening 57 centered on the optical axis) 5
In each cam groove 58 of the same number as the aperture blades 50 formed in 6,
Each bottle 52 is fitted.

Then, by relatively rotating the aperture blade container 53 and the cam member 56 with the optical axis as the center, each bin 52 moves along each cam groove 58, and there is a space between the aperture blade container 53 and the cam member 56. A plurality of housed aperture blades 50 are tilted around each rotation axis 51, and by overlapping the tilted aperture blades 50, the area of the effective diameter of the aperture formed in the center is changed, and the amount of light is adjusted. I have to.

[Problems to be Solved by the Invention] Incidentally, in such a conventional aperture mechanism, the external shape of the aperture blades 50 is set as shown in FIG. Stroke as shown. This is because the aperture blades have both the function of determining the effective diameter and the function of preventing light rays from leaking outside the effective diameter, so the size of the aperture blades cannot be reduced beyond a certain level.

Therefore, it is not possible to downsize the aperture blade container and the cam member.
The outer diameter of the lens barrel housing, which houses the diaphragm mechanism, cannot be made smaller, which is one of the obstacles to making lens barrels smaller and lighter.

An object of the present invention is to provide an aperture mechanism that can reduce the outer diameter of the entire aperture mechanism without causing light leakage from areas other than the effective aperture diameter.

[Means for Solving the Problems] A typical aperture mechanism for achieving the object of the present invention includes a first group of aperture blades for determining the effective diameter of the aperture consisting of a plurality of aperture blades, and a plurality of second aperture blades. A diaphragm mechanism in which a second diaphragm blade group consisting of diaphragm blades is spaced apart from each other along the optical axis direction, the second diaphragm blade group having a diameter other than the effective aperture diameter of the first diaphragm blade group. Each of the second aperture blades is formed to overlap with a non-overlapping portion of the aperture.

[Function] The diaphragm mechanism configured as described above has a second diaphragm blade group that blocks light from non-overlapping parts other than the diaphragm effective diameter, in addition to the first diaphragm blade group that determines the diaphragm effective diameter. , the entire aperture mechanism can be made smaller.

[Example] The present invention will be described in detail below based on an example shown in the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the aperture mechanism according to the present invention, FIG. 2 is a view taken in the direction of arrow A in FIG. 1, and FIG. 3 is a view taken in the direction of arrow B in FIG.

This embodiment includes an effective diameter determining aperture blade group consisting of a plurality of first aperture blades 1 for determining the effective aperture diameter, and a diaphragm blade group for preventing light leakage from other than the effective diameter in the effective diameter determining aperture blade group. It is composed of a group of aperture blades for preventing light leakage consisting of a plurality of second aperture blades 6.

A plurality of first aperture blades 1 constitute a group of aperture blades for determining the effective diameter (six in this embodiment), and a plurality of second aperture blades (six in this embodiment) constitute a group of aperture blades for preventing light leakage. Aperture blade 6
and are respectively arranged on the front and back sides of a common honeycomb 5 having a circular opening in the center, and as shown in FIG. is formed in a substantially constant arc shape, and a fixed dowel 3 serving as a rotation center is planted on one end side of the first shaft hole (not shown) for a group of aperture blades for determining an effective diameter, which is bored in the common honeycomb 5. A rotating dowel 4 is rotatably fitted into the first aperture blade l and is further embedded in the first aperture blade l.
is the cam groove 2b of the first wind turbine 2 with an opening 2a formed in the center.
By slidingly fitting the first windmill 2 into the common honeycomb 5 with the first windmill 2 as the optical axis center, the plurality of first diaphragm blades 1 are tilted around the fixed dowel 3, and the plurality of first aperture blades 1 are overlapped. The effective diameter is determined by

By the way, in the conventional diaphragm mechanism shown in Figure 8, the width of the base end of the diaphragm blade is widened (and when the diaphragm is narrowed down, it overlaps with the tip side of other diaphragm blades, thereby reducing the width between the other diaphragm blades. This is to prevent light leakage, but in this embodiment, the aperture blades 1 are formed in an arc shape with a substantially constant width to reduce the outer diameter of the aperture mechanism. When the aperture blade 1 is stopped down, a portion that does not overlap with the other first aperture blade 1 is created, and light leaks from there.Therefore, in this embodiment, the aperture group for determining the effective diameter is , the non-overlapping portion other than the aperture effective diameter formed by the plurality of aperture blades 1 is covered with a group of light leakage prevention aperture blades, and as shown in FIG. 2, the back side of the common honeycomb 5 is The second aperture blade 6 arranged in is formed in an arc shape with a substantially constant width, and has a fixed dowel 8 planted at one end thereof.
A second axial hole is formed in the common honeycomb 5 concentrically with the first axial hole.
A rotary dowel 9 rotatably fitted into a shaft hole (not shown) and implanted in the second aperture blade 6 slides into a cam groove 7b of the second wind turbine 7 in which an open lower a is formed in the center. By fitting the second windmill 7 with respect to the common honeycomb 5 with the second windmill 7 as the optical axis center, the plurality of second aperture blades 6 are tilted around the fixed dowel 8, and the aperture blades for determining the effective diameter are rotated. Group aperture blade 1
Covers the space other than the effective diameter of the aperture formed in between.

The second aperture blade 6 is formed shorter than the first aperture blade 1 so as not to affect the aperture effective diameter formed by the effective diameter determining aperture blade group.

In this embodiment, the engaging concave pieces 2c and 7c are provided at the same positions on the outer edges of the first wind turbine 2 and the second wind turbine 7, and the aperture drive lever (not shown) is engaged with these engaging concave pieces 2c and 7c. The first windmill 2 and the second windmill 7 are simultaneously rotated by driving the aperture drive lever, and the effective diameter determining aperture blade group and the light leakage prevention aperture blade group are simultaneously driven.

Therefore, according to this embodiment, since the width on the base end side of the first aperture blade 1 for determining the effective diameter of the aperture can be narrowed, the outer diameter of the entire aperture mechanism can be reduced accordingly.
Further, light leakage caused by the shape of the first aperture blade can be prevented by the second aperture blade 6, and a predetermined aperture effect can be obtained.

FIG. 4 is a longitudinal cross-sectional view of the other embodiment, and FIG. 5 is a view taken in the direction of arrow C.

In the embodiment described above, light leakage from the aperture blade group for determining the aperture effective diameter, which is made up of a plurality of first aperture blades 1, is prevented by the light leakage aperture blade group, which is made up of a plurality of second aperture blades 6. In this embodiment, light leakage is prevented from the aperture blade group for determining the aperture effective diameter, which is made up of a plurality of first aperture blades 1, without using a light leakage aperture blade group. Similarly, the fixed dowel 3 is rotatably fitted into the shaft hole (not shown) of the honeycomb 20, and the rotating dowel 4 is slidably fitted into the cam groove 21a of the windmill 21. A stretchable light-shielding cloth material 10 (indicated by diagonal lines in FIG. 5) is attached between the outer edge of the first aperture blade 1 and the inner edge of the honeycomb 20, and a predetermined area is set by driving the first aperture blade 1. The effective diameter of the aperture is obtained, and the cloth material 10 is stretched and expanded to prevent light leakage from areas other than the aperture effective diameter by the cloth material lO.

[Effects of the Invention] As explained above, according to the present invention, the aperture blades can be made smaller while preventing light leakage from areas other than the aperture effective diameter, so the outer diameter of the entire aperture mechanism can be reduced, and the aperture mechanism can be made smaller. This has the effect of making it more compact, and can contribute to making the lens barrel of a camera, for example, equipped with an aperture mechanism smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the aperture mechanism according to the present invention, FIG. 2 is a view taken in the direction of arrow A in FIG. 1, FIG. 3 is a view taken in the direction of arrow B in FIG. 1, and FIG. FIG. 5 is a longitudinal sectional view showing an embodiment of the invention, FIG. 5 is a view taken in the direction of arrow C in FIG. 4, and FIG.
7 is a view taken along arrow D in FIG. 6, and FIG. 8 is a view showing the aperture blades in FIG. 6. 1: Aperture blade 3: Fixed dowel 5: Common honeycomb 7; Second windmill 9: Rotating dowel 2: First windmill 4: Rotating dowel 6: Second aperture blade 8: Fixed dowel 1O: Cloth material. Figure Figure Figure Figure Figure Figure Figure

Claims (1)

[Claims] 1. A first aperture blade group for determining the effective diameter of the aperture and a second aperture blade group consisting of a plurality of second aperture blades are spaced apart from each other in the front and rear along the optical axis direction. The aperture mechanism is characterized in that the second aperture blade group is formed such that each of the second aperture blades overlaps a non-overlapping portion of the first aperture blade group other than the effective diameter of the aperture. Aperture mechanism. 2. A stretchable light-shielding sheet between a group of aperture blades for determining the effective diameter of the aperture consisting of a plurality of aperture blades formed in an arc shape with a substantially constant width and a holding member that holds each of the aperture blades. A diaphragm mechanism characterized by a material attached.