JP2607672B2 - Aperture mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a diaphragm mechanism for a camera lens.

[Prior Art] FIGS. 4 to 6 show a conventional aperture mechanism of a camera lens.

This is achieved by implanting a rotating shaft 51 called a fixed dowel on one side of each of the plurality of diaphragm blades 50, and planting a pin 52 called a rotating dowel on the other side, and forming a diaphragm blade container called a honeycomb. (A circular opening 54 is provided around the optical axis.) In each of the shaft holes 55 of the same number as the aperture blades 50 formed in 53,
A plurality of diaphragm blades 50 are accommodated so as to fit the respective rotating shafts 51, and diaphragm blades formed on a cam member 56 (having a circular opening 57 centered on the optical axis) called a windmill Each pin 52 is fitted in the same number of cam grooves 58 as 50.

By rotating the diaphragm blade container 53 and the cam member 56 relative to each other about the optical axis, each pin 52 is
Moving along 58, the plurality of diaphragm blades 50 housed between the diaphragm blade container 53 and the cam member 56 are tilted around each rotation shaft 51, and by the overlapping of the tilted diaphragm blades 50,
Change the area of the aperture effective diameter formed in the center part,
The amount of light is adjusted.

[Problem to be Solved by the Invention] In such a conventional aperture mechanism, the outer shape of the aperture blade 50 is changed so that light does not leak from a portion other than the aperture effective diameter even when the aperture is stopped down as shown in FIG. It is shown as follows. This is because the function of determining the effective diameter and the function of preventing light leakage other than the effective diameter are both provided, so that the size of the aperture blade cannot be reduced to some extent or more.

Therefore, the aperture blade container and the cam member cannot be reduced in size, and the outer diameter of the housing of the lens barrel having the built-in aperture mechanism cannot be reduced, which is one of the factors that hinder the reduction in size and weight of the lens barrel. Was.

SUMMARY OF THE INVENTION An object of the present invention is to provide a diaphragm mechanism capable of reducing the outer diameter of the entire diaphragm mechanism without causing light leakage from other than the effective diameter of the diaphragm.

[Means for Solving the Problems] A typical aperture mechanism for achieving the object of the present invention is:
A diaphragm mechanism in which a first diaphragm blade group composed of a plurality of first diaphragm blades and a second diaphragm blade group composed of a plurality of second diaphragm blades are spaced apart back and forth along the optical axis direction. The first aperture blade group moves to determine an aperture effective diameter, and the second aperture blade group moves to prevent light leakage from other than the aperture effective diameter. Cover portions that do not overlap with each other.

[Operation] The diaphragm mechanism configured as described above separates the first diaphragm blade group that determines the diaphragm effective diameter and covers the non-overlapping portions other than the diaphragm effective diameter of the first diaphragm blade group. Since the aperture blade group is provided, the size of the entire aperture mechanism can be reduced.

EXAMPLES Hereinafter, the present invention will be described in detail based on examples shown in the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of a diaphragm mechanism according to the present invention, FIG. 2 is a view as viewed from the direction of arrow A in FIG. 1, and FIG.
FIG.

In the present embodiment, a plurality of first
A group of aperture blades for determining an effective diameter (D ₁ ) comprising the aperture blade 1;
The effective diameter determining aperture blade group includes a plurality of second aperture blades 6 for preventing light leakage from other than the effective diameter.

A plurality of (six in this embodiment) first diaphragm blades 1 constituting an effective diameter determining diaphragm blade group, and a plurality of (six in this embodiment) second diaphragm blades constituting a light leakage prevention diaphragm blade group. The aperture blades 6 are arranged on both front and back sides of a common honeycomb 5 having a circular opening 5a at the center, and as shown in FIG. 3, the common honeycomb 5 is disposed on a front surface side of the first aperture blade 1 Is formed in an arc shape having a substantially constant width, and a fixed dowel 3 serving as a rotation center planted at one end thereof is bored in a common beehive 5 to form a first shaft hole for an effective diameter determining diaphragm blade group ( (Not shown), and a rotary dowel 4 implanted in the first diaphragm blade 1 is slidably fitted in a cam groove 2b of a first windmill 2 having an opening 2a formed in the center. Then, by rotating the first windmill 2 with respect to the common honeycomb 5 about the optical axis, the plurality of first aperture blades 1 move the fixed dowel 3 Slope in the heart, the effective diameter is determined by the superposition.

By the way, in the conventional diaphragm mechanism shown in FIG. 6, the width at the base end side of the diaphragm blade is widened, and when the diaphragm is stopped down, it overlaps with the distal end side of the other diaphragm blade, so that light leakage between other diaphragm blades is caused. In this embodiment, the outer diameter of the aperture mechanism is reduced by forming the aperture blade 1 in an arc shape having a substantially constant width, so that the first aperture for determining the effective diameter is reduced. Feather 1
When the aperture is stopped down, a portion that does not overlap with the other first aperture blades 1 occurs, and light leaks therefrom. For this reason, in this embodiment, in accordance with the driving of the effective diameter determining aperture blade group, non-overlapping portions other than the aperture effective diameter formed by the plurality of aperture blades 1 are covered with the light leakage prevention aperture blade group. As shown in FIG. 2, the second diaphragm blade 6 disposed on the back side of the common honeycomb 5 is formed in an arc shape having a substantially constant width, and is fixed to the fixed dowel planted at one end thereof. 8 is rotatably fitted in a second shaft hole (not shown) formed concentrically with the first shaft hole in the common honeycomb 5.
A rotary dowel 9 implanted in the aperture blade 6 of the second windmill 7 is slidably fitted in a cam groove 7b of a second windmill 7 having an opening 7a formed in the center.
By rotating the second windmill 7 with respect to the common honeycomb 5 about the optical axis, the plurality of second aperture blades 6 are fixed to the fixed dowels 8.
And covers the space other than the aperture effective diameter formed between the aperture blades 1 of the aperture blade group for determining the effective diameter.

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

In the present embodiment, engaging recesses 2c, 7c are provided at the same positions on the outer edges of the first windmill 2 and the second windmill 7, and an aperture drive lever (not shown) is engaged with these engaging recesses 2c, 7c. The first and second windmills 2 and 7 are simultaneously rotated by driving the aperture drive lever, and the aperture blade group for determining the effective diameter and the aperture blade group for preventing light leakage are simultaneously driven.

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

[Effects of the Invention] As described above, according to the present invention, the roles of the first aperture blade group and the second aperture blade group are divided, and the aperture effective diameter formed by the first aperture blade group. By covering the light leakage part formed in other than the second diaphragm blade group,
The aperture blades of the group of aperture blades can be made smaller, the overall diameter of the aperture mechanism can be reduced, and the aperture mechanism can be downsized. It can contribute to weight reduction.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a diaphragm mechanism according to the present invention, FIG. 2 is a view as seen from an arrow A in FIG. 1, FIG. 3 is a view as seen from an arrow B in FIG. 1, and FIG. FIG. 5 is a view taken in the direction of arrow D in FIG. 4, and FIG. 6 is a view showing the diaphragm blades in FIG. 1: First diaphragm blade (a plurality of first diaphragm blades constitutes a first diaphragm blade group) 2: First windmill 2a: Opening, 2b: Cam groove, 2c: Engagement piece 3: Fixed dowel, 4 : Rotating dowel 5: Common honeycomb, 5a: Opening 6: Second diaphragm blade (a plurality of second diaphragm blades constitute a second diaphragm blade group) 7: Second windmill 7a: Opening, 7b: Cam groove, 7c : Engagement concave piece 8: Fixed dowel 9: Rotating dowel D ₁ : Effective aperture

Claims (1)

(57) [Claims] A first group of aperture blades comprising a plurality of first aperture blades and a second group of aperture blades comprising a plurality of second aperture blades are spaced apart back and forth along the optical axis direction. A diaphragm mechanism, wherein the first diaphragm blade group moves to determine a diaphragm effective diameter, and the second diaphragm blade group moves to prevent light leakage from other than the diaphragm effective diameter. 1
A diaphragm mechanism that covers portions where the diaphragm blades do not overlap with each other.