JP2010230980A - Diaphragm apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diaphragm apparatus that improves qualities of blur and ghost shape. <P>SOLUTION: The diaphragm apparatus includes a rotary arm 5 and first to fourth diaphragm blades. The rotary arm 5 rotates about a rotation shaft CL1. The first diaphragm blade 1 includes a first pair of sides 1a and 1b which are connected to the rotary arm 5 and formed to define a V-shaped apex of an obtuse angle. The second diaphragm blade 2 includes a second pair of sides 2a and 2b which are connected to the rotary arm and formed to define a V-shaped apex of an obtuse angle. The third diaphragm blade 3 includes a third pair of sides 3a and 3b which are connected to the rotary arm and formed to define a V-shaped apex of an acute angle. The fourth diaphragm blade 4 includes a fourth pair of sides 4a and 4b which are connected to the rotary arm and formed to define a V-shaped apex of an acute angle. The area of an aperture defined by the first to fourth pairs of sides 1a, 1b, 2a, 2b, 3a, 3b, 4a and 4b surrounding the same varies in accordance with the rotation of the rotary arm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an aperture device, and more particularly, to an aperture device that is mounted on a video camera and has excellent blur and ghost shape.

2. Description of the Related Art Conventionally, many aperture devices for video cameras are composed of two diaphragm blades.
When there are two diaphragm blades, the opening shape formed by the diaphragm blades is usually a rhombus or a square.
In general, the closer the aperture shape formed by the diaphragm blades is to a circle, the more beautiful the so-called blur in soft focus and portrait, and the better the quality.
In addition, since the ghost shape generated under backlight is similar to the opening shape, the closer the opening shape is to a circle, the better the quality of the ghost shape.
Therefore, it is always desired to make the opening shape formed by the aperture blades as close to a circle as possible so as to improve the quality of the bokeh and ghost shape.

In response to this, a diaphragm device mounted on a lens used in a high-performance still camera such as a single-lens reflex camera has six or eight diaphragm blades arranged in the circumferential direction around the optical axis. Many of them have a structure that drives them so as to be separated from and in contact with the optical axis in a plane orthogonal to the optical axis.
According to this structure, since the opening shapes formed by the diaphragm blades are hexagonal or octagonal, respectively, the quality of the bokeh and ghost shape can be improved.

  However, if such a structure is adopted in which the diaphragm blades are arranged in the circumferential direction with respect to the optical axis and are separated from each other in the radial direction, the apparatus becomes large in the radial direction, so that downsizing and thinning are required. It is difficult to adopt it for still cameras and video cameras.

  Therefore, a diaphragm device that obtains a hexagonal aperture shape by arranging two pairs of four diaphragm blades facing each other with respect to the optical axis and driving them in a direction to be separated from each other on one axis passing through the optical axis is disclosed in Patent Document 1. Is disclosed.

JP-A-10-301159

Since the diaphragm device described in Patent Document 1 has a structure in which the diaphragm blades are driven so as to be separated from each other on one axis passing through the optical axis, it can be thinned in a direction perpendicular to the one axis.
In addition, since the aperture shape formed by the aperture blades is a hexagon, the quality of the bokeh and ghost shape is better than in the case of a rhombus or a square.
On the other hand, in the diaphragm device described in Patent Document 1, since the apex angle is an acute angle in the shape of the diaphragm blade, the stroke for closing the opposed diaphragm blade is long, and the device is downsized. There is room for improvement.
Furthermore, in recent years, as high-definition images have become widespread in general, video cameras have been demanded not only for reduction in size and thickness but also for improvement in image quality.
Therefore, further reduction in size and further improvement in the quality of blur and ghost shape are desired for the diaphragm device.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a diaphragm device that can further improve the quality of the blur and ghost shape. It is another object of the present invention to provide an aperture device that can further improve the quality of the bokeh and ghost shape and can be further reduced in size.

In order to solve the above problems, the present invention has the following configurations 1) to 4).
1) A rotating arm (5) that rotates in a forward / reverse direction around a predetermined rotation axis (CL1);
A first pair of sides (1a, 1a, 1) connected to the turning arm (5) and formed so as to approach each other as the apex angle (θ1) becomes an obtuse V shape and is farther from the turning axis (CL1). A first diaphragm blade (1) having 1b);
A second pair of sides (2a, 2b) connected to the rotating arm (5) and formed so as to approach each other as the apex angle (θ2) is an obtuse V shape and closer to the rotating shaft (CL1). ) A second diaphragm blade (2) having
A third pair of sides (3a, 3b) connected to the turning arm (5) and formed so as to approach each other as the vertex angle (θ3) becomes an acute V shape and is further away from the turning shaft (CL1). ) A third aperture blade (3) having
A fourth pair of sides (4a, 4b) connected to the rotating arm (5) and formed so as to approach each other as the apex angle (θ2) has an acute V shape and is closer to the rotating shaft (CL1). A fourth diaphragm blade (4) having
An opening window formed by being surrounded by the first to fourth pairs of sides (1a, 1b, 2a, 2b, 3a, 3b, 4a, 4b) as the rotating arm (5) rotates. The diaphragm device (50) is configured to change the area of K1).
2) The first pair of sides (1a, 1b) and the second pair of sides (2a, 2b) are separated from each other as the turning arm (5) rotates in the forward and reverse directions. The diaphragm device (50) according to 1), wherein the third pair of sides (3a, 3b) and the fourth pair of sides (4a, 4b) are configured to be separated from each other. It is.
3) The aperture device (50) according to 1) or 2), wherein the opening window (K1) is a regular octagon.
4) Having connecting sides (3c) (4c) that connect the third pair of sides (3a, 3b) or the fourth pair of sides (4a, 4b) so as not to intersect at the apex (P3, P4) The diaphragm device (50) according to any one of 1) to 3), wherein:

  According to the present invention, it is possible to further improve the quality of the bokeh and ghost shape. Further, it is possible to further improve the quality of the bokeh and ghost shape, and to further reduce the size.

It is a perspective view which shows the Example of the aperture_diaphragm | restriction apparatus of this invention. It is a top view for demonstrating the aperture blade in the Example of the aperture_diaphragm | restriction apparatus of this invention. It is a top view for demonstrating the effect in the Example of the aperture_diaphragm | restriction apparatus of this invention. It is a top view for demonstrating the operation | movement in the Example of the aperture_diaphragm | restriction apparatus of this invention. It is a perspective view for demonstrating the operation | movement in the Example of the aperture_diaphragm | restriction apparatus of this invention.

  The preferred embodiments of the present invention will be described with reference to FIGS.

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

In FIG. 1, a base plate 6 is a plate-like member formed with the axis line CLn direction as a longitudinal direction.
The base plate 6 has a circular opening 6k centered on the intersection of the axis CLt and the axis CLt orthogonal to the axis CLn.
The aperture device 50 is disposed on the optical path of the imaging device such that the center of the opening 6k coincides with the optical axis of the imaging device such as a video camera.
The base plate 6 has two pairs of guide pins 6a to 6d that protrude along the axis CLn at positions symmetrical to the axis CLn.
A rotating arm 5 is provided on the lower side of the base plate 6 in FIG. 1 so as to be rotatable clockwise and counterclockwise (in the direction of the arrow RT1) around the rotation axis CL1.
The rotation arm 5 is connected to the galvanometer 7 and is driven to rotate in the direction of the arrow RT1 within a predetermined angle range about the rotation axis CL1 by the galvanometer 7.
The rotation by the galvanometer 7 is controlled from the imaging device side so that the imaging device on which the diaphragm device 50 is mounted has an aperture value for capturing a good image.

The rotating arm 5 is provided with four projecting drive pins.
Specifically, drive pins 5b and 5a are provided from the rotation axis CL1 side on the left side of FIG. 1 with respect to the rotation axis CL1, and the rotation axis CL1 side is provided on the right side of FIG. Drive pins 5c and 5d are provided.

The base plate 6 is provided with four aperture blades engaged with the guide pins 6a to 6d and the drive pins 5a to 5d.
Specifically, the four blades are, in order from the side far from the base plate 6 (the front side in FIG. 1), the first blade 1, the second blade 2, the third blade 3, and the fourth blade 4. It is.
The diaphragm blades 1 to 4 are light shielding means for shielding light that passes through the opening 6k by moving back and forth inside the opening 6a and controlling the amount of light passing through the aperture 6a.

Each of the diaphragm blades 1 to 4 is provided with a slit that extends long in the direction of the axis CLn and engages with each of the guide pins 6a to 6d.
Accordingly, the blades 1 to 4 are guided by the guide pins 6a to 6d and are movable in the direction of the axis CLn.

The blades 1 to 4 are engaged with the drive pins 5a to 5d as follows.
That is, the first blade 1 engages only with the drive pin 5b, the second blade 2 engages only with the drive pin 5c, the third blade 3 engages only with the drive pin 5a, The fourth blade 4 is engaged only with the drive pin 5d.
Accordingly, each of the blades 1 to 4 is positioned at a predetermined location in the direction of the axis CLn according to the rotation angle of the rotation arm 5 as the rotation arm 5 rotates.

Next, the shape of each blade | wing 1-4 is demonstrated using Fig.2 (a)-(d).
FIGS. 2A and 2B show the rotating arm 5 and the first and second blades 1 and 2.
2C and 2D show the rotating arm 5 and the third and fourth blades 3 and 4.

The first blade 1 is a member that is hatched in FIG.
The first blade 1 has a pair of sides 1a and 1b that are symmetrical with respect to the axis CLn and form an apex angle θ1 at the edge. The apex angle θ1 is an obtuse angle and is 135 degrees in the embodiment, and the apex P1 is on the side far from the rotation axis CL1 with respect to the sides 1a and 1b.
The first blade 1 is engaged with the drive pin 5b in the lower part of FIG.

The 2nd blade | wing 2 is a member which attached the oblique line in FIG.2 (b).
The second blade 2 has a pair of sides 2a and 2b that are symmetrical with respect to the axis line CLn and form an apex angle θ2. The apex angle θ2 is an obtuse angle and is 135 degrees in the embodiment. The apex P2 is on the side closer to the rotation axis CL1 with respect to the sides 2a and 2b.
The second blade 2 is engaged with the drive pin 5c in the lower part of FIG.

The 3rd blade | wing 3 is a member which attached the oblique line in FIG.2 (c).
The third blade 3 has a pair of sides 3a and 3b that are symmetrical with respect to the axis CLn and form an apex angle θ3 at the edge. The apex angle θ3 is an acute angle and is 45 degrees in the embodiment. The apex P3 is on the side farther from the rotation axis CL1 than the sides 3a and 3b.
Further, a side 3c that is orthogonal to the axis CLn and connects the sides 3a and 3b is provided.
The 3rd blade | wing 3 is engaging with the drive pin 5a in the downward direction of FIG.2 (c).

The 4th blade | wing 4 is a member which attached the oblique line in FIG.2 (d).
The fourth blade 4 has a pair of sides 4a and 4b that are symmetrical about the axis CLn and form an apex angle θ4 at the edge. The apex angle θ4 is an acute angle and is 45 degrees in the embodiment. The apex P4 is closer to the sides 4a and 4b from the rotation axis CL1.
Further, a side 4c that is orthogonal to the axis CLt and connects the sides 4a and 4b is provided.
The fourth blade 4 is engaged with the drive pin 5d in the lower part of FIG.

In the above-described configuration, when the first to fourth blades 4 are combined, as shown in FIG. 3 (a), a regular eight consisting of eight sides 1a, 1b, 2a, 2b, 3a, 3b, 4a, 4b. A square opening window K1 is obtained.
In FIG. 3A, a circle C1 inscribed in the opening window K1 is also shown, and a region between the opening window K1 and the circle C1 is black.
The smaller the area of the black coating, the closer the aperture shape of the aperture is to a circle, and the quality of the bokeh and ghost shape can be further improved.
As a comparative example, FIG. 3C shows a regular hexagonal opening window K10 and a circle C10 inscribed therein in a conventional diaphragm device. Similarly, the area between the opening window K10 and the circle C10 is painted black.
Comparing the black areas of FIG. 3 (a) and FIG. 3 (c), it is clear that the opening window K1 of the embodiment is closer to the circular opening. Therefore, it can be seen that the diaphragm device of the embodiment can improve the quality of the blur and the ghost shape well.

Further, the size of the opening window K1 can be arbitrarily changed according to the rotation angle of the rotation lever 5.
The sides 1 a and 1 b of the first diaphragm blade 1 and the sides 2 a and 2 b of the second diaphragm blade 2 are separated from each other by the rotation of the rotation lever 5.
Further, the sides 3 a and 3 b of the third diaphragm blade 3 and the sides 4 a and 4 b of the fourth diaphragm blade 4 are separated from each other by the rotation of the rotation lever 5.
Then, each separation / separation is performed at the same time, and the size of the opening window 1k surrounded by each side changes.
FIG. 4A shows a state where the rotation lever 5 is at the maximum clockwise position within the allowable rotation range, and FIG. 4N shows a state where the rotation lever 5 is at the maximum counterclockwise position. 4 (b) to 4 (m) show the state of the position of each rotation lever 5 in which the interval between them is roughly divided.
That is, the aperture window K1 is the minimum aperture (open end) in FIG. 4A, and the aperture window K1 is the maximum aperture (minimum aperture) in FIG.
5 (a), (d), (f), and (j) are perspective image diagrams corresponding to FIGS. 4 (a), (d), (f), and (j), respectively. FIG. 5 (n) shows a state in which the stroke is further expanded from the state of FIG. 4 (n) to completely close the opening window K1.

Here, when the distances from the rotation axis CL1 of the rotation lever 5 to the drive pins 5b, 5a, 5c, and 5d are Lb, La, Lc, and Ld, respectively,
Lb: La: Lc: Ld = 1: 2.41: −2.41: −1
Is set, the shape of the opening window K1 is similar regardless of the rotational position of the rotation lever 5.

The apex angles θ1 to θ4 of the first to fourth blades 1 to 4 may be set as follows.
That is, θ1 = θ2 = 120 degrees and θ3 = θ4 = 60 degrees.
The aperture window K2 obtained under this condition is composed of eight sides 1a, 1b, 2a, 2b, 3a, 3b, 4a and 4b, and an octagon having an inner angle of 120 degrees and 150 degrees. Become.

FIG. 3B shows an opening window K2 and a circle C2 inscribed therein. In FIG.3 (b), the area | region between both is made black.
Also in this case, although the blacked area is larger than that of the regular octagonal opening window K1 (see FIG. 3A), the blacked area is smaller than that of the conventional opening window K10 (see FIG. 3C). It can be seen that the quality of the bokeh and ghost shape can be improved.

When θ1 = θ2 = 120 degrees and θ3 = θ4 = 60 degrees, the distances from the rotation axis CL1 of the rotation lever 5 to the drive pins 5b, 5a, 5c, and 5d are Lb, La, Lc, and Ld, respectively. The ratio of each other
Lb: La: Lc: Ld = 1: 1.73: -1.73: -1
Is set, the shape of the opening window K2 is similar regardless of the rotational position of the rotation lever 5.

In the embodiment, the third blade 3 is provided with a side 3c, and the fourth blade 4 is provided with a side 4c.
That is, the side 3a and the side 3b in the third blade 3 are connected so as not to intersect at the vertex P3 through the side 3c, and the side 4a and the side 4b in the fourth blade 4 are connected through the side 4c. They are connected so as not to intersect at the vertex P4.

As a result, as shown in FIG. 2C, the third diaphragm blade 3 has a stroke St1 that is a movement distance in the direction of the axis CLn necessary to completely close the opening window K1 when there is no side 3c. On the other hand, when the side 3c is provided, the stroke St2 in the direction of the axis CLn necessary for completely closing the opening window K1 is shortened by ΔSt3.
Similarly, the stroke of the fourth diaphragm blade 4 is shortened by ΔSt4 as shown in FIG. 2 (d).

  Therefore, by providing the side 3c and the side 4c, the diaphragm device 50 can shorten the outer dimension in the direction of the axis CLn by the length indicated by ΔSt3 + ΔSt4, and can be miniaturized.

In this way, the sides 3c and 4c function as stroke shortening means.
At a stage where the area is secured to the extent that the opening window K1 is present, the sides 3c and 4c do not contribute to the formation of the opening window K1. For example, in the stage shown in FIGS. 4 (a) to 4 (l).
On the other hand, in the state shown in FIGS. 4M and 4N where the area of the opening window K1 is minimized, the sides 3c and 4c constitute the side of the opening window K1, so that the octagon is not maintained.
Therefore, the position where the stroke shortening means is provided may be in a range where the aperture window K1 shape on the small aperture side does not practically affect the image quality.

Repetitively explaining the first to fourth diaphragm blades,
The first diaphragm blade is connected to the rotating arm, and has a first pair of sides formed so as to approach each other as the distance from the rotating shaft increases.
The second diaphragm blade is connected to the rotating arm, and has a second pair of sides formed such that the apex angle is an obtuse V shape and the closer to the rotating shaft, the closer to each other.
The third diaphragm blade is connected to the rotating arm, and has a third pair of sides formed so as to approach each other as the apex angle becomes an acute V-shape and the distance from the rotating shaft increases.
The fourth diaphragm blade is connected to the rotation arm, and has a fourth pair of sides formed so that the apex angle is an acute V-shape and the closer to the rotation axis, the closer to each other.

  The embodiment of the present invention is not limited to the configuration and procedure described above, and it goes without saying that modifications may be made without departing from the scope of the present invention.

Instead of providing the sides 3c and 4c, the side 3a and the side 4b may be connected with the arc (so-called R) or the side 4a and the side 4b.
The apex angles θ1 to θ4 of the blades 1 to 4 are not limited to the angles described above.
By increasing the apex angles θ3 and θ4 of the third and fourth blades 3 and 4, a regular octagon can not be obtained, but the stroke can be shortened. Therefore, priority is given to circular approximation or miniaturization by shortening the stroke. A numerical value may be determined according to priority.
In any case, the ratio of the distances Lb, La, Lc, and Ld can be set so that the size of the opening window is changed in a similar manner.
Further, the shape of the aperture window is not limited to an octagon, and if a stroke shortening means is provided, the moving distance of the diaphragm blades can be shortened and the diaphragm device can be miniaturized.

1-4 1st-4th blade | wing 1a, 2a, 3a, 4a Side 1b, 2b, 3b, 4b Side 1c, 2c side (stroke shortening means)
5 Rotating Arms 5a to 5d Drive Pin 6 Base Plates 6a to 6d Guide Pin 6k Opening 7 Galvanometer 50 Diaphragm CL1 Rotating Axis CLn, CLt Axis K1 Opening Window P1 to P4 Vertex θ1 to θ4 Vertical Angle

Claims (4)

A rotating arm that rotates in a forward and reverse direction around a predetermined rotation axis;
A first diaphragm blade connected to the pivot arm and having a first pair of sides formed so as to be closer to each other as the distance from the pivot axis is an obtuse V-shaped apex angle;
A second diaphragm blade connected to the pivot arm and having a second pair of sides formed so as to approach each other as the pivot axis approaches the pivot axis with an obtuse angle V-shape;
A third diaphragm blade connected to the pivot arm and having a third pair of sides formed so as to be closer to each other as the distance from the pivot axis becomes an acute V-shaped apex angle;
A fourth diaphragm blade having a fourth pair of sides connected to the pivot arm and formed so as to approach each other as the apex angle is V-shaped and closer to the pivot axis;
A diaphragm device having a configuration in which an area of an opening window formed by being surrounded by the first to fourth pairs of sides is changed with rotation of the rotation arm.   The first pair of sides and the second pair of sides come into contact with each other and the third pair of sides and the fourth pair of sides as the turning arm rotates in the forward and reverse directions. 2. The diaphragm device according to claim 1, wherein the two are arranged so as to be in contact with each other.   3. A diaphragm according to claim 1, wherein the opening window is a regular octagon.   The diaphragm device according to any one of claims 1 to 3, further comprising a connecting side that connects the third pair of sides or the fourth pair of sides so as not to intersect at a vertex. .

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