JP6760446B2 - Aperture unit, lens barrel and camera - Google Patents

Description

The present invention relates to an aperture unit, a lens barrel and a camera.

There is a diaphragm mechanism having a main diaphragm that adjusts the amount of incident light flux to the camera according to a set diaphragm value, and a sub diaphragm that adjusts the open diaphragm diameter to an open diaphragm value according to the focal length. Conventionally, the number of blades constituting these main diaphragms and sub diaphragms is the same (see Patent Document 1).
The aperture shape of the diaphragm is preferably close to a circle. By increasing the number of blades, the opening can be made close to a circular shape, but if the number of blades of the main diaphragm is increased, the blades overlap more when the diaphragm is stopped, and the operability deteriorates.

JP-A-2000-25093

The diaphragm unit is engaged with a plurality of first blades driven based on the diaphragm value and the plurality of the first blades, and the rotatable first member and the first member are rotated according to the diaphragm value. A driving unit and a plurality of second blades driven based on an open aperture value according to a focal length are provided, and the number of the second blades is larger than the number of the first blades.
Further, the lens barrel is configured to include the above aperture unit.
Further, the camera is configured to include the above aperture unit.

It is the schematic of the camera including the aperture mechanism of an embodiment. It is a partial cross-sectional view of the drawing mechanism. It is an exploded perspective view of the diaphragm mechanism. It is a front view of the blade holding plate. It is a figure which showed the example of the relationship between the focal length and the open F value determined by the open aperture diameter of a secondary diaphragm. It is a figure which showed the opening formed by the secondary diaphragm, (a) is this embodiment, (b) is a comparative form. (A) is a partially enlarged view of FIG. 6 (a), and (b) is a partially enlarged view of FIG. 6 (b).

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like.
FIG. 1 is a schematic view of the camera 1 including the aperture mechanism 30 of the embodiment.
As shown in the figure, the camera 1 includes a camera body 10 and a lens barrel 20 that can be attached to and detached from the camera body 10. In the present embodiment, the lens barrel 20 can be attached to and detached from the camera body 10, but the present invention is not limited to this, and the lens barrel 20 and the camera body 10 may be integrated.

The camera body 10 includes an image sensor 11 that converts an optical image of a subject into an electric signal.
The lens barrel 20 includes a photographing optical system 21 including a zoom lens, and an aperture mechanism 30 according to the present embodiment. The photographing optical system 21 and the aperture mechanism 30 move in the optical axis OA direction according to the focal length.

FIG. 2 is a partial cross-sectional view of the diaphragm mechanism 30. FIG. 3 is an exploded perspective view of the diaphragm mechanism 30.
The diaphragm mechanism 30 has a main diaphragm 31 mainly responsible for adjusting the amount of light, and a sub diaphragm 32 provided separately from the main diaphragm 31 to correct the open diaphragm diameter according to zooming or focusing.
The diaphragm mechanism 30 further includes a base member 33, a main diaphragm cam plate 34, a holding plate 35, a diaphragm actuator 36, a blade holding plate 37, a secondary diaphragm cam plate 38, and a holding plate rotating member 39. , A spring member 41 is provided.

The base member 33 serves as a base on which each member is arranged, and is fixed to a fixed portion (not shown) of the lens barrel 20.
The main diaphragm 31 forms an opening by combining seven blades 31a, and determines a diaphragm diameter other than the open diaphragm. Protrusions 31b and 31c are provided on the subject side of each blade 31a of the main diaphragm 31 in the optical axis OA direction and on the camera body 10 side, respectively.
The main diaphragm cam plate 34 is provided with a main diaphragm cam 34a in which protrusions 31c of each blade 31a on the camera body side are inserted and moved.

The holding plate 35 fixes the main diaphragm cam plate 34 in a rotatable state about the center of the optical axis OA and in the direction of the optical axis OA.
The diaphragm actuator 36 is a drive source for driving the blades 31a by rotating the main diaphragm cam plate 34 to open and close the opening of the main diaphragm 31. In the throttle actuator 36, the gear 36a provided at the tip and the gear 34d provided on the main throttle cam plate 34 are engaged with each other. Further, the throttle actuator 36 is fixed to the holding plate 35 with a screw 40.

The secondary diaphragm 32 is a diaphragm provided for correcting the open diaphragm diameter according to zooming and focusing, and has nine blades 32a, which is a different number from the blades of the main diaphragm 31. Protrusions 32b and 32c are provided on the subject side and the camera body 10 side of each blade 32a of the sub diaphragm 32 in the optical axis OA direction, respectively.
The sub-throttle cam plate 38 is provided with a sub-throttle cam 38a.

FIG. 4 is a front view of the blade holding plate 37. As shown in the figure, the blade holding plate 37 is a ring plate-shaped member. The blade holding plate 37 is provided with seven holes 37a for fitting the protrusions 31b attached to the main diaphragm 31, and nine holes 37b for fitting the protrusions 32c attached to the sub-throttle 32. , A total of 16 holes are provided.
The holes 37a for the protrusions 31b of the main diaphragm 31 are provided on the inner diameter side, and the holes 37b for the protrusions 32c of the sub diaphragm 32 are provided on the outer diameter side of the holes 37a and are evenly arranged along the circumference. There is.

The holding plate rotating member 39 is a rod member provided with a cam surface 39a, and the subject side is thinner than the camera body 40 side.
The spring member 41 is for attaching the blade holding plate 37 to the cam surface 39a of the holding plate rotating member 39. By urging the spring member 41, for example, when the aperture mechanism 30 moves along the optical axis OA due to a change in the focal length, the blade holding plate 37 can be rotated by the inclination of the cam surface 39a. The diameter of the open diaphragm to be formed can be set to an appropriate diameter according to the focal length.

Here, the open F value and the focal length will be described. FIG. 5 is a graph showing an example of the relationship between the open F value and the focal length determined by the open aperture diameter of the sub diaphragm 32. As shown in the figure, when the focal length is wider than the focal length f1, the sub-aperture 32 is in the state of the maximum open diameter, and the open F value is maintained in the state of, for example, F3.5.

On the other hand, when the focal length is on the tele side larger than f1, the aperture diameter gradually decreases as the focal length increases, and when the focal length reaches the maximum (tele end), the open F value becomes F5.6. Become.

By changing the aperture diameter of the sub-aperture 32 in conjunction with the movement of the photographing optical system 21 in this way, the open F value can be set to an appropriate value according to the focal length.

FIG. 6 is a diagram showing an opening formed by the sub-throttle 32. (A) is a diagram showing an opening formed by nine blades according to the present embodiment, and (b) is a diagram showing an opening formed by seven blades in the comparative embodiment.
Further, FIG. 7 (a) is a partially enlarged view of FIG. 6 (a), and FIG. 7 (b) is a partially enlarged view of FIG. 6 (b). The dotted line in the figure is the inscribed circle L of the opening formed by the blade 31a. In the figure, the distance d is the maximum distance between the inscribed circle L and the edge portion R of the opening formed by the blade 32a.
As shown in the figure, the maximum separation distance d1 when formed by the nine blades of the present embodiment as shown in FIG. 7 (a) and the seven blades of the comparative form as shown in FIG. 7 (b). Comparing with the maximum separation distance d2 when formed by, d1 <d2.
That is, when the number of blades 32a is nine as in the present embodiment, the opening formed by the blades 32a is closer to a circle than in the case of seven blades.

Therefore, according to the present embodiment, it is possible to provide a lens barrel 20 having a more beautiful bokeh condition, for example, the open diaphragm diameter can be made closer to a circle as compared with the case where the sub diaphragm 32 has a seven-blade configuration. it can.
Even if the number of blades of the secondary diaphragm is increased in this way, the aperture is not reduced unlike the main diaphragm because the secondary diaphragm defines the open aperture diameter, and even if the number of blades is increased. It is less likely that the main aperture will affect the operability.
As described above, according to the present embodiment, it is possible to provide an aperture unit, a lens barrel, and a camera whose open aperture shape created by the sub-aperture side is close to a circular diameter.

(Transformed form)
Not limited to the embodiments described above, various modifications and changes as shown below are possible, and these are also within the scope of the present invention.
In the present embodiment, an example in which the number of blades 32a of the sub-diaphragm 32 is 9 has been described, but the present invention is not limited to this, and for example, 11 blades may be used. When the main diaphragm is, for example, five, the sub diaphragm may be seven.
Further, in the present embodiment, the auxiliary diaphragm blade 32a is driven by the actuator 36, and the main diaphragm blade 31a is driven by the holding plate rotating member 39. However, the main diaphragm blade and the secondary diaphragm blade are driven by the actuator or the holding. It is not limited to either of the plate rotating members.
Further, although the holding plate rotating member 39 is determined to rotate the blade holding plate 37, the auxiliary drawing cam plate 38 may be rotated.
The embodiment and the modified form can be used in combination as appropriate, but detailed description thereof will be omitted. Further, the present invention is not limited to the embodiments described above.

1: Camera, 10: Camera body, 11: Imaging element, 20: Lens barrel, 21: Imaging optical system, 30: Aperture mechanism, 31: Main aperture, 31a: Blade, 31b: Projection, 31c: Projection, 32: Sub diaphragm, 32a: blade, 32c: protrusion, 33: base member, 34: main diaphragm cam plate, 34a: main diaphragm cam, 34d: gear, 35: holding plate, 36: actuator, 36a: gear, 37: Blade holding plate, 37a: hole, 37b: hole, 38: auxiliary drawing cam plate, 38a: auxiliary drawing cam, 39: holding plate rotating member, 39a: cam surface, 41: spring member

Claims (8)

Multiple first blades driven based on the aperture value,
A first member that can rotate by engaging with a plurality of the first blades,
A drive unit that rotates the first member according to the aperture value,
It is equipped with a plurality of second blades that are driven based on the open aperture value according to the focal length.
The number of the second blades is larger than the number of the first blades. Multiple first blades driven based on the aperture value,
A plurality of second blades driven based on the open aperture value according to the focal length, and
A second member that engages with the plurality of the second blades and moves in the optical axis direction while rotating according to the focal length is provided .
The number of the second blades is larger than the number of the first blades . The second member engages with a plurality of the first blades.
The aperture unit according to claim 2 . The position where the first blade and the second member engage is on the inner diameter side in the radial direction centered on the optical axis from the position where the second blade and the second member engage.
The aperture unit according to claim 3 . Multiple first blades driven based on the aperture value,
It is equipped with a plurality of second blades that are driven based on the open aperture value according to the focal length.
A plurality of said first blade, Ri formable der smaller opening than the opening formed by a plurality of the second blade,
The number of the second blades is larger than the number of the first blades . The size of the aperture formed by the plurality of second blades varies depending on the focal length.
The aperture unit according to any one of claims 1 to 5 . A lens barrel comprising the aperture unit according to any one of claims 1 to 6 . A camera including the aperture unit according to any one of claims 1 to 6 .

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