JPH11167140A - Diaphragm for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm for a camera capable of permanently preventing the generation of a ghost caused by the mutual reflection of the image pickup surface of an image pickup element and an ND filter by forming the ND filter, so as to make its section a circular-arc shape and providing stoppers for preventing the elongation of the ND filter, in an aperture blade to which the ND filter is attached, so as to prevent the secular change in shape of the ND filter. SOLUTION: A projection part 30 is formed on one end part, of the ND filter 22 and a pin hole formed in the projection part 30 is fitted on a positioning pin 32 provided on the aperture blade 10. The other end part, of the ND filter 22 is restrained by two stoppers 34 provided on the aperture blade 10. Therefore, the elongation of the ND filter 22 caused by the secular change can be prevented by the stoppers 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm device for a camera, and more particularly to a diaphragm device provided with an ND filter for reducing the amount of light on diaphragm blades.

[0002]

2. Description of the Related Art Conventionally, in an optical machine such as a camera or a video camera, an ND filter is attached to an aperture blade in order to prevent a problem such as deterioration of image quality due to an extremely small aperture during high-brightness shooting. It has been known. Since the ND filter is located in the optical path when the aperture is reduced and reduces the light amount, it prevents the aperture from becoming extremely small even during high-luminance shooting.

Conventionally, when such an ND filter is mounted on an aperture blade, the image pickup surface of the image pickup device and the ND filter are arranged in parallel, so that ghost occurs due to mutual reflection between the image pickup surface and the ND filter. There was a problem. For this reason, the ND filter is tilted so that the ND filter and the imaging surface are not parallel (see FIG. 6).
No. 1-53739), and an ND filter that is bent in an inverted V shape so that the ND filter and the imaging surface are not parallel (Japanese Utility Model Laid-Open No. 3-63125) have been proposed.

[0004]

However, in each of the above-mentioned ND filters proposed so far, only the base end of one end is bonded to the diaphragm blade.
When mounting the D filter at an angle
No. 53739) has a problem in that the stability at the time of bonding is poor due to its own weight, the bonding operation is difficult, and the inclination angle differs depending on the product. In the case of an ND filter bent in an inverted V-shape, since the portion other than the base end of the ND filter is not fixed to the diaphragm blade, the ND filter is bent in an inverted V-shape due to aging. There is a problem that the portion gradually expands and the effect of preventing ghosts and the like is reduced. In addition, the conventional mounting structure of the ND filter has a problem that the mounting position is unstable and varies from product to product.

The present invention has been made in view of such circumstances, and prevents aging of the shape of an ND filter to prevent ghost caused by mutual reflection between an imaging surface of an image sensor and the ND filter. It is another object of the present invention to provide a diaphragm device for a camera which can prevent the ND filter from being mounted on each product and prevents the mounting position of the ND filter from varying.

[0006]

According to the present invention, in order to achieve the above object, an ND filter is attached to a diaphragm blade forming an aperture opening, and the ND filter reduces the amount of light passing through the opening. An aperture device for a camera is characterized in that the ND filter is bent so as to have an inverted V-shape or arc shape, and both ends of the bent ND filter are fixed to aperture blades.

According to the present invention, the ND filter is bent so as to have an inverted V-shape or an arc shape, thereby preventing mutual reflection between the imaging surface and the ND filter, and forming the bent ND filter. By fixing both ends of the filter to the diaphragm blades, it is possible to prevent the shape of the ND filter from changing due to aging, and to maintain the effect of preventing ghosts and the like permanently.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a diaphragm device for a camera according to the present invention. FIG. 1 is an assembled perspective view of a diaphragm device of a camera to which the present invention is applied. The aperture 2 shown in the figure has six aperture blades 10, 10,... Formed in a substantially crescent shape,
These aperture blades 10 are held between the donut-shaped aperture frame 4 and the chrysanthemum seat 6 in a superimposed manner. Are fixed together with the aperture frame 4 and the chrysanthemum seat 6 to an aperture frame 8 formed in a cylindrical shape.

At the base end of each of the aperture blades 10, a pivot pin 12 is implanted. The rotation pin 12 is rotatably attached to a bearing hole 4A formed in the aperture frame 4. Thus, the aperture blade 10 is positioned on the aperture frame 4 so as to be swingable. A dowel pin 14 protrudes from the aperture blade 10 on a side opposite to the rotation pin 12. The dowel pin 14 is a long hole-shaped guide hole 6 formed in the chrysanthemum seat 6.
A is engaged.

Therefore, when the chrysanthemum 6 is swung clockwise (in the direction of arrow A) about the optical axis 16, the dowel pin 14 of the diaphragm blade 10 swings along the guide hole 6 A of the chrysanthemum 6.
The aperture blade 10 is pivoted about the rotation pin 12 as an optical axis 16
Swings in the direction approaching. Thereby, the opening becomes smaller. When the opening is to be enlarged, the chrysanthemum 6 is moved to the optical axis 1.
6 is pivoted counterclockwise (direction of arrow B). As a result, the dowel pin 14 is inserted into the guide hole 6A.
And the aperture blade 10 swings in a direction away from the optical axis 16 with the rotation pin 12 as a swing fulcrum, so that the aperture becomes large. The Kikuza 6 is rotated by a motor (not shown) by a function such as an auto iris.

An ND filter 22 is attached to the uppermost one of the diaphragm blades 10, 10,.... The ND filter 22 is located at the center (optical axis 16) of the opening when the opening becomes small during high-brightness imaging. This prevents the aperture from becoming too small by reducing the amount of light during high-brightness shooting, and prevents the occurrence of a hunting phenomenon and the like.

Next, the shape and mounting structure of the ND filter 22 will be described. FIG. 2 shows an ND filter 2
FIG. 3 is an enlarged perspective view of the mounting portion of FIG.
It is AA sectional drawing in. As shown in FIG. 2, the aperture blade 10 is formed in a substantially crescent shape, and a cut portion 10A is formed substantially in the center of the inner periphery. The ND filter 22 is designed to be attached to the cut portion 10A.

As shown in the sectional view of FIG. 3, the ND filter 22 has a cross section curved in an arc shape.
By forming the ND filter 22 in an arc shape as described above, light reflected from the imaging surface can be diffused by the ND filter 22, so that ghost due to mutual reflection between the imaging surface and the ND filter 22 can be appropriately prevented. Can be prevented. In addition, compared to a conventionally proposed ND filter having an inverted V-shaped cross section, the effect of diffusing the reflected light from the imaging surface is higher when formed in an arc shape, so that image quality deterioration due to ghosting is more effectively reduced. Can be prevented.

A projection 30 is formed at one end of the ND filter 22, and a positioning pin 32 provided on the aperture blade 10 is provided in a pin hole 30A provided in the projection 30.
Is inserted. At the tip of the positioning pin 32, a locking claw 3
2A are formed, and the positioning pin 32 and the pin hole 30 are formed.
Once A is fitted, it has a structure that does not easily come off. As a result, the ND filter 22 and the aperture blade 10 are integrally formed, and the ND filter 22 can be easily attached to the aperture blade 10 without bonding with an adhesive or the like.

The other end of the ND filter 22 is
The stop is provided by two stoppers 34 provided on the aperture blade 10. By providing the stoppers 34, 34 in this manner, the ND filter 22
The positioning pins 32 are
The movement in the rotation direction about the axis is regulated, and the positioning pin 3
It is properly positioned at a predetermined position by the stopper 2 and the stoppers 34,34. At the same time, the stoppers 34, 34 can prevent the ND filter 22 from being stretched and flattened due to aging.
Inconveniences such as a ghost caused by mutual reflection with the light source 2 are permanently prevented. When the diaphragm blade 10 is made of plastic, the positioning pin 32 and the stopper 34 may be formed integrally with the diaphragm blade 10.

FIG. 4 is a perspective view showing another embodiment of the mounting structure of the ND filter 22. As shown in FIG. FIG.
The same or similar members as those of the embodiment shown in FIG. As shown in the figure, three protrusions 40, 40 having locking claws 40A at both ends of the ND filter 22 are provided.
40, and these projections 40, 4
Positioning holes 42, 42, 42 are provided at three places on the diaphragm blade 10 corresponding to 0 and 40. Then, the respective projections 40, 40, 40 of the ND filter 22 are aligned with the positioning holes 42, 4
2 and 42, the ND filter 22 is operated by the locking claw 40A of each projection 40 so that
Fixed integrally to the With the mounting structure of the ND filter 22, the same effect as in the above embodiment can be obtained.

In the above embodiment, the ND filter 2
2 is arc-shaped, but as described in the section of “Prior Art”, even when the cross-section of the ND filter is an inverted V-shape, the ND filter has the same structure as the above embodiment. The filter can be attached to the aperture blade 10, and problems such as aging of the shape and variations in the attachment position can be prevented. FIG. 5 shows an inverted V section.
FIG. 4 is a perspective view when the attachment structure shown in FIG. 2 is applied to a letter-shaped ND filter. As shown in the figure, the ND filter 50 having an inverted V-shaped cross section is positioned at a predetermined position by positioning pins 52 provided on the diaphragm blade 10 and stoppers 54, 54, and the ND filter 50 is provided by the stoppers 54, 54. The extension of the bent portion is prevented.

In the above embodiment, the ND filter 22 is fixed to the aperture blade 10 by a pin or the like. However, even when both ends of the ND filter 22 are fixed only by the adhesive, the shape of the ND filter 22 may change. It is possible to prevent.

[0019]

As described above, according to the camera diaphragm apparatus of the present invention, the ND filter is bent so as to have an inverted V-shape or an arc shape, so that the imaging surface and the ND filter can be formed.
By preventing mutual reflection between the filters, and by fixing both ends of the bent ND filter to the aperture blades, the shape of the ND filter is prevented from changing due to aging, and the ghost filter is permanently removed. The prevention effect can be maintained. In addition, by fixing the ND filter to the aperture blade with the locking structure, the ND filter can be mounted at a desired position without causing variations among products.

[Brief description of the drawings]

FIG. 1 is an assembled perspective view of a diaphragm device of a camera to which the present invention is applied.

FIG. 2 is an enlarged perspective view showing a mounting portion of an ND filter.

FIG. 3 is a sectional view taken along the line AA in FIG. 2;

FIG. 4 is a perspective view showing another embodiment of the mounting structure of the ND filter.

FIG. 5 is a perspective view showing a mounting structure of an ND filter of another shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Aperture blade 22 ... ND filter 30 ... Protrusion 32 ... Positioning pin 34 ... Locking claw

Claims (2)

[Claims] An aperture device for a camera, wherein an ND filter is attached to aperture blades forming an aperture opening, and the amount of light passing through the aperture is reduced by the ND filter. A diaphragm device for a camera, wherein the diaphragm is formed to have an arc shape, and both ends of the bent ND filter are fixed to diaphragm blades. 2. An end of the ND filter is fixed to the diaphragm blade by a locking structure.
Camera aperture device.