JPH04345149A - Diaphragm for camera - Google Patents

Abstract

PURPOSE:To improve horizontal resolution without changing an F-number value in the small diaphragm of an iris. CONSTITUTION:In this diaphragm for a camera 10 on which an opening part 12a is formed on a diaphragm plate 12 placed in a lens optical system C for the camera, the opening part 12a is freely opened/closed by a diaphragm blade reciprocating along the diaphragm plate 12, and an ND filter 20 is fixed so as to be projected to a diaphragm part opening/closing the opening part 12a of the diaphragm plate 12 of the diaphragm blade, a pair of the left and right diaphragm blades 13 and 14 are freely horizontally slide-moved along the diaphragm plate 12. On the other hand, the opening shape of the projecting part 21 of the ND filter 20 is imitated to the opening shape of the diaphragm part 13a of the diaphragm blade 12 of the left side as much as possible, to project the projecting part 21 by prescribed length compared with the diaphragm part 13a of the diaphragm blade 13.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called side opening type aperture device (iris) used in cameras such as video cameras.

0002

2. Description of the Related Art For example, in the iris of a camera, an ND filter (Neutral Density Filter) is installed in the diaphragm part of the diaphragm blade, which has an equal absorption rate for all wavelengths of light and is intended to reduce the amount of light.
lter) is fixed and is used when overexposure occurs even at the minimum aperture, or when the brightness exceeds the coverage range of EE (Electric Eye). this,
To explain in detail with reference to FIGS. 5 and 6, reference numeral 100 is a diaphragm plate placed in the lens optical system of the camera, and this diaphragm plate 100 has a circular opening 100a formed therein. This opening 100a can be opened and closed by a pair of diaphragm blades 101 and 102 that move up and down along the diaphragm plate 100 and move toward and away from each other. An ND filter 110 that protrudes a predetermined length from the arc-shaped aperture portion 101a of the upper aperture blade 101 is fixed with adhesive. This ND filter 110 is formed in a substantially fan shape, and the arc-shaped protrusion 110a is an opening of the aperture plate 100 formed between each aperture part 101a, 102a of the pair of upper and lower aperture blades 101, 102. It is designed to protrude into the inside of the 100a. As shown in FIG. 6, this pair of aperture blades 10
As the so-called vertical opening type aperture device in which the aperture blades 1 and 102 move up and down becomes smaller, the pair of upper and lower aperture blades 10
In the opening 100a of the diaphragm plate 100 whose area is variable between the diaphragm parts 101a and 102a of 1,102, the arc-shaped protrusion 110a of the ND filter 110
The amount of light from the lens optical system is reduced by increasing the area occupied by the lens.

0003

[Problems to be Solved by the Invention] In the above conventional camera aperture device, when the aperture is small, the pair of upper and lower aperture blades 10
The left and right opening width (aperture degree) H of the opening 100a of the diaphragm plate 100 can be varied between the diaphragm parts 101a and 102a of 1 and 102, respectively. The same shape as the ND filter used in this vertical opening type aperture device is used, but the lens barrel of the camera is thinner.
If it is applied to a horizontal opening type in which a pair of aperture blades move horizontally along the aperture plate, the protrusion 110a of the ND filter 110 has an arcuate convex shape, so it can be varied by the pair of left and right aperture blades. The aperture (horizontal width) of the aperture of the diaphragm plate becomes narrower (H' in Figure 6 indicates the aperture when this vertical opening type iris is applied to horizontal opening, H'< H). ), a problem arises in which horizontal resolution deteriorates due to diffraction, etc.

[0004] Therefore, the present invention aims to achieve an F number equivalent to the conventional one (where D is the aperture of the lens and f is the focal length of the lens) at a small aperture even in a side-opening type in which the aperture blades move horizontally.
/D is called the F number, and the brightness of the image is 2 of the F number.
The present invention provides an aperture device for a camera that can improve the horizontal resolution by a value (inversely proportional to the power of the diaphragm).

[0005]

[Means for solving the problem] An aperture is formed in a diaphragm plate placed in the optical system of a camera, and this aperture can be freely opened and closed by a diaphragm blade that moves back and forth along the diaphragm plate. In a camera aperture device in which an ND filter is fixed so as to protrude into an aperture section that opens and closes an opening of the aperture plate of the blade, the aperture blade is made horizontally movable along the aperture plate; The aperture shape of the protruding portion is made as close as possible to the aperture shape of the diaphragm portion of the diaphragm blade, and is made to protrude from the diaphragm portion of the diaphragm blade by a predetermined length.

[0006]

[Operation] The horizontal width of the aperture of the diaphragm plate, which can be varied by the diaphragm blades, is widened as in the conventional case, and the horizontal resolution can be improved without changing the F-number value when the aperture is small.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. In FIGS. 1 and 2, reference numeral 10 denotes an aperture device, which is attached to approximately the middle of the lens barrel 1 of the video camera. This diaphragm device 10 has a substantially box-shaped cabinet 11 in which a diaphragm plate 12 is integrally molded within a frame portion 11a. This diaphragm plate 12 is formed into a horizontally long rectangular shape, and a circular opening 12a is formed around the lens optical system C of the video camera in the center thereof. Further, in the upper and lower positions of one side surface of the aperture plate 12 on the CCD side (not shown),
Pairs of pins 15, 15 and 16, 16 are protrudingly provided to support the left and right pair of aperture blades 13, 14, respectively, so that the left and right pair of aperture blades 13, 14 can slide horizontally.

The left diaphragm blade 13 has a diaphragm portion 13a opening in a substantially arcuate concave shape at the center of the right end. Also,
The above-mentioned pair of pins 15, 1 are provided on the upper side of the aperture blade 13.
A pair of horizontally elongated holes 13b, 13b are formed to be inserted through the hole 5, and a vertical hole 13c is formed in the center of the left end. An ND filter 20 is fixed to the aperture part 13a side of the left aperture blade 13 with adhesive, and its protruding part 21 protrudes by a predetermined length into the opening from the aperture part 13a. The opening shape of the protruding part 21 of this ND filter 20 is made as close as possible to the opening shape of the aperture part 13a of the aperture blade 13, and as shown in FIG. Projection part 21b and arcuate lower projection part 21
It is formed into a substantially heart shape with c.

Further, the right aperture blade 14 has a substantially V-shaped aperture portion 14a formed at the center of the left side. Further, on the lower side of this aperture blade 14, the above-mentioned pair of pins 16 are provided.
, 16 are formed, and a vertical hole 14c is formed in the lower left extending portion.

[0010] An IG meter 17 is installed in the upper left cylindrical corner portion 11b of the cabinet 11. A lever 18 is fixed to a rotating shaft 17a of this meter 17. The protruding pin 18a of the lever 18 has a shaft portion 11c integrally formed in the cabinet 11.
Round hole 1 of a disc-shaped rotating body 19 rotatably supported by
9a is inserted and engaged. A pair of upper and lower pins 19b and 19c protruding from the rotating body 19 are inserted into and engaged with the vertical holes 13c and 14c of the left and right pair of aperture blades 13 and 14, respectively. By rotating the rotating body 19 in the forward and reverse directions, the pair of left and right aperture blades 13 and 14 can be moved toward and away from each other in the horizontal direction, so that the opening area of the aperture 12a of the aperture plate 12 can be varied. ing.

Aperture device 10 for video camera according to the above embodiments
According to the above, when the rotating body 19 is rotated forward or backward by the meter 17, the pair of left and right aperture blades 13, 14 slide horizontally along the aperture plate 12, and the pair of aperture blades 13,1
The opening area of the opening 12a of the diaphragm plate 12 is varied by the four diaphragm portions 13a and 14a. As shown in FIG. 3, as the pair of left and right aperture blades 13 and 14 move closer to each other to become a smaller aperture, the proportion of the aperture area of the aperture 12a of the ND filter 20 increases. The aperture shape of the aperture part 21 of this ND filter 20 is made as close as possible to the aperture shape of the aperture part 13 of the left aperture blade 13, and has a concave middle protrusion part 21b at the center of the aperture of the aperture part 21. Therefore, even if the F number value is large,
The amount of protrusion of the aperture section 21 of the ND filter 20 relative to the opening area of the opening section 12a is small. Therefore, even if the pair of left and right aperture blades 13 and 14 are moved horizontally, the resolution can be improved to the same level as or even higher than that of the conventional vertically moving (vertical opening) type.

In this way, the pair of left and right aperture blades 13 and 14 are made horizontally movable along the aperture plate 12, and the aperture part 13a of the left aperture blade 13 opens and closes the opening 12a of the aperture plate 12. , the protrusion 21 of the ND filter 20 that reduces the amount of light from the lens optical system C of the camera is fixed with adhesive so as to protrude by a predetermined length, and the aperture shape of the protrusion 21 of the ND filter 20 is shaped like the above-mentioned left diaphragm. Since the aperture shape of the aperture part 13a of the aperture plate 12 is formed as close as possible to the aperture shape of the aperture part 13a of the blade 13, the horizontal direction of the aperture of the aperture part 12a of the aperture plate 12, which is varied by the aperture part of the pair of left and right aperture blades 13 and 14, is The width H can be widened, and the horizontal resolution can be further improved with the same F-number value as the conventional one when using a small aperture.

Although the embodiment described above is applied to an aperture device for a video camera, it may also be applied to aperture devices for various cameras such as still cameras and electronic still cameras. In addition, although we have described a horizontally opening type diaphragm device in which the aperture of the diaphragm plate is opened and closed by a pair of left and right aperture blades, this application is applicable to a horizontally opening type diaphragm device in which the aperture in the diaphragm plate is opened and closed by a single aperture blade. You can also do that.

[0014]

As described above, according to the camera aperture device of the present invention, the aperture blades are made horizontally movable along the aperture plate having an opening in the optical system of the camera, and the aperture of the aperture blades is The protruding part of the ND filter is fixed to the aperture part that opens and closes the opening of the plate so as to protrude by a predetermined length, and
Since the aperture shape of the protruding part of the D filter is formed to be as close as possible to the aperture shape of the aperture part of the aperture blade, the horizontal width of the aperture of the aperture plate of the aperture plate can be varied by the aperture blade. can be made as wide as before, and when using a small aperture, the horizontal resolution can be further improved with the same F-number value as before.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an aperture device for a video camera showing an embodiment of the present invention.

FIG. 2 is a perspective view of a lens barrel of a video camera to which the aperture device is attached.

FIG. 3 is an explanatory diagram of the shapes of the aperture blades and ND filter of the aperture device.

FIG. 4 is a comparative diagram of the shapes of the aperture blades and ND filter of the aperture device described above and the shape of a conventional ND filter.

FIG. 5 is a schematic explanatory diagram of a conventional aperture device.

FIG. 6 is a schematic explanatory diagram of the conventional aperture device when the aperture is small.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10... Aperture device of a camera, 12... Aperture plate, 12a... Aperture, 13... Aperture blade, 13a... Aperture part, 20... ND filter, 21... Projection part, C... Lens optical system of a camera.

Claims (1)

[Claims] Claim 1: An aperture is formed in a diaphragm plate placed in the optical system of a camera, and the aperture is freely opened and closed by a diaphragm blade that moves back and forth along the diaphragm plate, and the diaphragm of the diaphragm blade N so that it protrudes into the aperture part that opens and closes the opening of the plate.
In a camera diaphragm device to which a D filter is fixed, the diaphragm blades are made horizontally movable along the diaphragm plate, and the aperture shape of the protruding part of the ND filter can be changed to the aperture shape of the diaphragm part of the diaphragm blade. A diaphragm device for a camera, characterized in that the diaphragm blades are protruded by a predetermined length from the diaphragm portion of the diaphragm blades.