JPH10301159A - Diaphragm device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm device whose aperture is formed to a regular hexagonal shape and having a good out-of-focus image. SOLUTION: The diaphragm device is provided with four aperture blades 1, 2; 3 and 4, a base plate 6 and a rotary arm 5, and the aperture blade 1 is provided with a light shielding edge part 1f, the aperture blade 2 is provided with light shielding edge parts 2f and 2g, the aperture blade 3 is provided with light shielding edge parts 3f and 3g, the aperture blade 4 is provided with a light shielding edge part 4f, and the rotary arm 5 is shifted so that the ratio of the aperture blades 1, 2, 3 and 4 may be 1:-2:-1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aperture device for a video camera or the like, and more particularly to an aperture stop with improved blur.

[0002]

2. Description of the Related Art As a light amount adjusting device such as a diaphragm device of a video camera, the light amount adjusting device is linearly close to each other on a plane perpendicular to the optical axis.
Two aperture blades slidably provided in the direction of separation (relatively opposite direction), and the light receiving area changes in accordance with the approach / separation of the two blades formed on each of these two blades And the two blades are close to each other
2. Description of the Related Art There is conventionally known a device provided with a drive mechanism that slides in a direction in which the device is separated.

An example of this type of apparatus will be described with reference to FIG. FIGS. 3A to 3E are plan views showing states from a state in which the aperture is completely opened to a state in which the diaphragm is completely closed in five stages. In these figures, 5
Reference numeral 1 denotes a circular opening formed in the main plate 50;
Reference numeral 1 denotes an aperture blade, 30a denotes a substantially raindrop-shaped opening formed in the aperture blade 30, and 31a denotes a notch formed in the aperture blade 31.

The diaphragm blade 30 has a driving slit 3
0b and guide slits 30c to 30e are formed, the drive slit 30b is engaged with a pin 41b implanted in a rotating arm 41 which is driven and rotated by the galvanometer 40, and the guide slits 30c to 30e Are engaged with the guide pins 52, 54, 55 implanted in. Similarly, a driving slit 31b and guide slits 31c to 31e are formed in the diaphragm blade 31, and the driving slit 31b
Are engaged with pins 41a implanted in a rotating arm 41 which is rotated by being driven by a galvanometer 40, and guide slits 31c to 31e are guide pins 52, 5
3, 54 are engaged.

Accordingly, when the galvanometer 40 is excited and rotates clockwise in the state shown in FIG.
1 also rotates clockwise together, the diaphragm blade 30 is displaced downward, the diaphragm blade 31 is displaced upward, and the aperture 5 of the base plate 50 is displaced upward.
1 will be closed.

[0006]

The conventional diaphragm device described above has a relatively small number of parts and a small mechanical load, and is therefore excellent in terms of cost reduction and power saving. It is widely used in recent video cameras and the like. However, because the diaphragm is composed of two diaphragm blades,
As shown in FIGS. 3B to 3D, the aperture shape in the process of narrowing down must be substantially rhombic, which causes a problem of so-called “blur taste”. This is because the blurring effect largely depends on not only the defocus characteristic of the photographing lens but also the aperture shape of the aperture.

In general, it is said that it is better to maintain the similarity of the shape itself, to have a core, and to gradually fade from the core toward the periphery. When a subject having a high-luminance part such as a sunbeam in the background is photographed with a shooting lens incorporating the conventional aperture device described above, the sunbeam is blurred and formed into an approximate rhombus similar to the aperture shape of the aperture. This results in an unnatural image. So, conventionally,
The aperture shape of the aperture is ideally circular, and efforts have been made to approach this. SUMMARY OF THE INVENTION An object of the present invention is to provide a diaphragm device having a regular hexagonal opening shape and good bokeh.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the invention according to claim 1 is directed to "the first to fourth four aperture blades and the first to fourth aperture blades, A holding member for holding the fourth four diaphragm blades so as to be displaceable in the same linear direction; and a driving means for driving the first to fourth four diaphragm blades in the linear direction. The first diaphragm blade has a first light-shielding edge forming an angle of 90 degrees with respect to the linear direction, and the second diaphragm blade has a second light-shielding edge forming an angle of +30 degrees with respect to the linear direction. A first V-shaped notch comprising an edge and a third light-shielding edge forming an angle of -30 degrees with respect to the linear direction; A first V-shaped notch comprising a fourth light-shielding edge forming an angle of +30 degrees and a fifth light-shielding edge forming an angle of -30 degrees with respect to the linear direction; , The fourth diaphragm blade has a sixth light-shielding edge forming an angle of 90 degrees with respect to the linear direction, and the driving means includes: The first to fourth four aperture blades are respectively 1: 2: -2:
A diaphragm device configured to be displaced at a ratio of -1. "

According to a second aspect of the present invention, the driving means comprises a rotating arm and a first to a fourth arm mounted on the rotating arm.
A distance from the rotation center of the rotation arm to the first drive pin is L1, a distance from the rotation center of the rotation arm to the second drive pin is L2, The distance from the rotation center of the rotation arm to the third drive pin is L3
When the distance from the rotation center of the rotation arm to the fourth drive pin is L4, L1: L2: L3: L4 = 1: 2: -2: -1 and the first Drive pin is engaged with the first aperture blade, the second drive pin is engaged with the second aperture blade, and the third drive pin is engaged with the third aperture blade. The diaphragm device according to claim 1, wherein the fourth drive pin is engaged with the fourth diaphragm blade. ”.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a diaphragm device according to the present invention will be described below with reference to FIGS. FIG.
FIG. 2 is an exploded perspective view showing an embodiment of the aperture device according to the present invention, and FIGS. 2A to 2E each show five stages from a fully opened state to a completely closed state. FIG.

In FIG. 1, reference numerals 1 to 4 represent first
To the fourth diaphragm blade, reference numeral 6 is a main plate, reference numeral 8 is a cover,
Reference numeral 5 denotes a rotating arm, and reference numeral 7 denotes a galvanometer.
In the first diaphragm blade 1, an opening 1a, a driving slit 1b,
Guide slits 1c to 1e are formed, and a linear light-shielding edge 1f orthogonal to the longitudinal direction of the guide slits 1c to 1e is provided at the upper edge of the opening 1a. An opening 2a, a driving slit 2b, guide slits 2c to 2e, and a relief slit 2h are formed in the second diaphragm blade 2, and the upper edge of the opening 2a is formed in the longitudinal direction of the guide slits 2c to 2e. Straight light-shielding edges 2f and 2g having an angle of ± 30 degrees are provided.

The third diaphragm blade 3 has a notch 3
a, a drive slit 3b, guide slits 3c to 3e, and a relief slit 3h are formed, and the notch 3a has a linear light-shielding edge 3f that forms an angle of ± 30 degrees with the longitudinal direction of the guide slits 3c to 3e. 3 g are provided.

The fourth diaphragm blade 4 has a notch 4
a, a drive slit 4b, and guide slits 4c to 4e are formed, and the notch 4a is provided with a linear light-shielding edge 4f orthogonal to the longitudinal direction of the guide slits 3c to 3e. The base plate 6 has a thin box shape for accommodating the first to fourth diaphragm blades, and has a circular opening 6a for determining an opening diameter of the diaphragm device and each guide slit 1 of the four diaphragm blades 1 to 4.
Guide pins 6 which are fitted to c-1e, 2c-2e, 3c-3e, 4c-4e, respectively, and guide each aperture blade linearly.
b to 6e are planted. The galvanometer 7 is further fixed to the base plate 6, and the rotating arm 5 is fixed to the output shaft of the galvanometer 7.

The rotating arm 5 has a driving pin 5b engaging with the driving slit 1b of the diaphragm blade 1, a driving pin 5a engaging with the driving slit 2b of the diaphragm blade 2, and a driving slit 3b of the diaphragm blade 3. And a drive pin 5c that engages with the drive slit 4b of the aperture blade 4, respectively. Here, the drive pin 5b penetrates through the escape slit 2h of the aperture blade 2 and engages with the drive slit 1b of the aperture blade 1, and the tip of the drive pin 5c engaged with the drive slit 4b of the aperture blade 4 These drive pins do not interfere with the aperture blades because they penetrate the escape slits 3h of the aperture blades 3.

The distances from the rotation axis of the rotation lever 5 to the drive pins 5b, 5a, 5d and 5c are L1 and L, respectively.
When L2, L3, and L4 are set, L1: L2: L3: L4 = 1: 2: -2: -1. The cover 8 has a circular opening 8a for determining the opening diameter of the aperture device and driving pins 5a to 5a.
Escape slits 8b to 8e of 5c are formed to hold four diaphragm blades 1 to 4 housed in the main plate 50.

Since the aperture device of the present invention is configured as described above, when the drive lever is rotated by the galvanometer 7, the ratio of the displacement amounts of the first to fourth aperture blades is 1: 2:-. 2: -1, the opening / closing operation is performed while maintaining the shape of the opening as a regular hexagon, as shown in FIG.

[0017]

As described above, according to the aperture device of the present invention, the aperture shape of the aperture can be maintained in a nearly circular and substantially regular hexagonal shape in almost all situations. This makes it possible to realize a photographing lens with good bokeh. Further, in the diaphragm device of the present invention,
A regular hexagonal aperture does not rotate with a change in aperture diameter, so even if the brightness changes with a change in the shooting scene with a video camera or the like, the ghost image of the aperture only changes its aperture diameter. And a natural image can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a diaphragm device of the present invention.

FIG. 2 is a plan view showing the diaphragm device of the present invention from an open state to a closed state in five stages.

FIG. 3 is a plan view showing a conventional diaphragm device from an open state to a closed state in five stages.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st aperture blade 2 2nd aperture blade 3 3rd aperture blade 4 4th aperture blade 5 Rotating arm 6 Base plate 7 Galvanometer 8 Cover 30 Aperture blade 30a Opening 30b Drive slit 30c Guide slit 30d Guide slit 30e Guide Slit 31 Aperture blade 31a Notch 31b Guide slit 31c Guide slit 31d Guide slit 40 Galvanometer 41 Rotating arm 50 Base plate 51 Circular opening

Claims (2)

[Claims] 1. A first to fourth four diaphragm blades, a holding member for holding the first to fourth four diaphragm blades so as to be displaceable in the same linear direction, and the first to fourth diaphragm blades. A driving means for driving the four aperture blades in the linear direction, wherein the first aperture blades have a first light-shielding edge forming an angle of 90 degrees with respect to the linear direction; The second diaphragm blade has a first light-shielding edge that forms an angle of +30 degrees with respect to the linear direction and a third light-shielding edge that forms an angle of -30 degrees with respect to the linear direction. The third diaphragm blade has a fourth light-shielding edge that forms an angle of +30 degrees with respect to the linear direction and a fifth light-shielding edge that forms an angle of -30 degrees with respect to the linear direction. A second V-shaped notch formed of a light-shielding edge and opposed to the first V-shaped notch; and the fourth diaphragm blade is 90 degrees with respect to the linear direction. An aperture device having a sixth light-shielding edge forming an angle, wherein the driving means displaces the first to fourth four aperture blades at a ratio of 1: 2: -2: -1 respectively; . 2. The driving means comprises a rotating arm and first to fourth four driving pins implanted on the rotating arm, and the first driving pin is pivoted from the center of rotation of the rotating arm. The distance from the rotation center of the rotation arm to the second drive pin is L2, and the distance from the rotation center of the rotation arm to the third drive pin is L3. When the distance from the rotation center of the rotation arm to the fourth drive pin is L4, L1: L2: L3: L4 = 1: 2: -2: -1 is set, A drive pin is engaged with the first diaphragm blade and the second
The third drive pin is engaged with the third aperture blade, and the fourth drive pin is engaged with the fourth aperture blade. The diaphragm device according to claim 1, wherein: