JP2016133627A - Diaphragm device, and lens device having the same, and imaging device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm device that reduces a reciprocating difference and allows the amount of light to be highly accurately adjusted without increasing the number of components.SOLUTION: A diaphragm device comprises: a plurality of stop blades that a rotation center member and a drive pin are fixed; a support member that supports the rotation center member so as to allow the stop blade to freely rotate; and a cam member that has a cam groove with which the drive pin of the stop blade engages. A prescribed direction to the diaphragm device is defined, and in the respective stop blades, a trajectory of a centre of gravity of the stop blade when the stop blade is driven is parallel to the prescribed direction, and does not cross a straight line passing through a rotation centre.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a diaphragm device used in a photographic lens device, and more particularly to a diaphragm device whose aperture diameter is changed by a rotation operation, a lens device having the diaphragm device, and an imaging device.

  Conventionally, a plurality of diaphragm blades having a rotation shaft are arranged at equal angular intervals on the same circumference, and the diaphragm aperture formed by overlapping the inner edge portions of the diaphragm blades is changed by rotation around the rotation shaft of the diaphragm blades. A diaphragm device is known. In such a diaphragm device, the diaphragm blade is provided with a rotation center pin and a drive pin, and the position of the drive pin with respect to the rotation center pin supported at the fixed position is determined by a cam groove formed on the disc-shaped cam plate. A guiding structure is common.

  The light amount adjustment function of the lens device is desired to have high accuracy of the index value and the aperture value. Therefore, the diaphragm device is required to have a small difference in aperture area between when the aperture value is changed from the opening side to the closing side and when the aperture value is changed from the closing side to the opening side. In the present specification, this difference is referred to as a round-trip difference.

  In order to reduce the reciprocal difference, Patent Document 1 discloses a structure that improves the aperture accuracy by urging the aperture blade using a leaf spring and eliminating backlash between the drive pin and the cam groove. Further, Patent Document 2 discloses a structure that improves the diaphragm accuracy by pressing the bent part of the diaphragm blade against the holding ring or the like and eliminating the backlash between the diameter convex part and the guide groove by the elastic force of the diaphragm blade. ing.

JP-A-6-265773 JP-A-6-123909

  However, when the structure as in Patent Document 1 is applied to the diaphragm device, there is a problem that the entire diaphragm device including the urging mechanism becomes complicated and large. Further, when a structure like the diaphragm device of the above-mentioned Patent Document 2 is applied, there is a risk that the aperture shape may be collapsed or the diaphragm blades may be plastically deformed due to the influence of elastic deformation.

In order to solve the above-described problem, the diaphragm device of the present invention includes:
A plurality of aperture blades to which the rotation center member and the drive pin are fixed;
A support member that supports the rotation center member so that the aperture blade is rotatable, and a cam member having a cam groove that engages with the drive pin of the aperture blade;
In a diaphragm device comprising:
A predetermined direction is defined for the diaphragm device;
Each of the diaphragm blades
The locus of the center of gravity of the diaphragm blade when the diaphragm blade is driven does not intersect with a straight line that is parallel to the predetermined direction and passes through the rotation center of the diaphragm blade.
A diaphragm device characterized by that.

  According to the present invention, the reciprocal difference in the relationship between the position of the operating ring and the aperture value can be obtained regardless of the operating direction of the operating ring that operates the aperture value between the opening side and the closing side without increasing the number of parts. It is possible to provide a diaphragm device that can reduce the amount of light with high accuracy.

It is a disassembled perspective view of the aperture mechanism in Example 1 of the present invention. It is a longitudinal cross-sectional view of the aperture mechanism in Example 1 of this invention. It is a view from the drive pin side of the aperture blade in Example 1 of this invention. It is a combination figure of the aperture blade in Example 1 of this invention. It is a figure of the blade support cylinder (blade support member) in Example 1 of this invention. It is a figure of the cam board in Example 1 of this invention.

[Example 1]
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.

  An exploded perspective view of this embodiment is shown in FIG. 1, and a longitudinal sectional view is shown in FIG. As shown in FIG. 1, the diaphragm device includes a diaphragm blade support cylinder (support member) 1, a plurality of diaphragm blades 2, a cam plate (cam member) 3, and a presser fitting 4. As shown in FIG. 2, the plurality of diaphragm blades 2 are sandwiched between the cam plate 3 and the blade support tube 1.

  FIG. 3 shows a view from the side of the diaphragm blade 5 where a drive pin 5b, which will be described later, is convex. The diaphragm blade 5 has a rotation center pin (rotation center member) 5a projecting on one surface and a drive pin 5b projecting on the facing surface. FIG. 4 shows a plurality of diaphragm blades 2. The diaphragm blades drive the diaphragm device so that the locus 5d of the center of gravity 5c of each diaphragm blade when the aperture shape is changed does not intersect with a straight line parallel to a predetermined direction and passing through the center of each rotation center pin 5a. The blade shape and the blade attachment position. Here, the predetermined direction is a direction that is defined in advance with respect to the diaphragm device when the lens device is attached to the lens device, and the vertical direction in the posture in which the lens device is normally used.

  In this embodiment, the plurality of diaphragm blades 2 are composed of six diaphragm blades 5 and are incorporated so as to alternately overlap as shown in FIG. FIG. 5 shows the diaphragm blade support cylinder 1. The rotation center pin 5a is engaged with an engagement hole (rotation bearing portion) 1a provided in the diaphragm blade support cylinder 1 so as to be freely rotatable (circular movement in both directions).

  FIG. 6 shows the cam plate 3. A cam plate 3 is provided on the drive pin 5 b side of the plurality of diaphragm blades 2 so as to be rotatable with respect to the diaphragm blade support cylinder 1 about the optical axis center o. The cam plate 3 has six cam grooves 3a, and the drive pin 5b of each diaphragm blade 5 is engaged with the cam groove 3a. Here, the optical axis is a term indicating the optical axis of the lens device to which the diaphragm device of the present invention is mounted and fixed. When the diaphragm device is mounted on the lens device, it is normally mounted so that the center of the opening formed by the diaphragm blades coincides with the optical axis of the lens device to be mounted. Therefore, in the description of the present specification, the optical axis position is treated as synonymous with the position of the center of the opening formed by the diaphragm blades.

  With the above structure, when the cam plate 3 is rotated around the optical axis center o with respect to the diaphragm blade support cylinder 1, the drive pin 5b of the diaphragm blade 5 is guided to the cam groove 3a. Thereby, the aperture blade 5 rotates around the rotation center pin 5a.

  As described above, the center of gravity of each diaphragm blade when the aperture shape is changed does not intersect with the straight line passing through the center of each rotation center pin in parallel with the predetermined direction. On the other hand, the direction of the moment around the center of each rotation center pin 5a due to gravity is always one direction in the operation region. As a result, the driving pin of each blade is always driven along the one wall 3b of the cam groove by the gravity G shown in FIG. it can.

  This effect is achieved by satisfying the relationship that the locus of the center of gravity of each diaphragm blade does not intersect with the straight line parallel to the predetermined direction and passing through the center of each rotation center pin. Regardless.

  In addition, when the aperture device has a close function that shields light by setting the aperture area to zero, the locus of the center of gravity is parallel to the predetermined direction in the operation region from the close to the predetermined amount and the open side. It may intersect with a straight line passing through the center of the rotation center pin of the blade. In that case, in the light amount adjustment region for adjusting the aperture diameter for the purpose of adjusting the amount of light passing through the diaphragm device, the index value and the diaphragm value are set when the diaphragm device is driven to the open side and the small diaphragm side by the above configuration. The round-trip difference in the relationship can be reduced. In the operation area of the close function until the aperture area is made zero by further rotating the aperture blade from the light amount adjustment area, there is almost no case of shooting in the state of a small aperture near the close, when the aperture blade is driven, In this area, there is no need to reduce the reciprocal difference in the relationship between the position of the diaphragm operating ring (index value) and the diaphragm value to adjust the light quantity (adjusting the opening area) with high accuracy. Thus, the degree of freedom in designing the diaphragm device can be increased.

  Further, in the embodiment, the diaphragm blade 2 is provided with the rotation center pin projecting, and the rotation center pin is engaged with the engagement hole 1a of the diaphragm blade support cylinder 1. It is not limited to this. Even if the diaphragm blade support cylinder 1 is provided with a rotation center pin and the rotation center pin is engaged with a rotation center hole (rotation bearing) provided in the diaphragm blade, the same effect can be obtained. it can.

  Further, in an imaging device including a lens device having the aperture device of the present invention and an imaging device that receives light from the lens device and the lens device, the reciprocal difference in the relationship between the aperture index value and the aperture value can be reduced and increased. Enables accurate light quantity adjustment. In a state where the aperture device is mounted on the lens device, the predetermined direction set in advance in the aperture device is a vertical direction when the lens device is used in a predetermined posture for normal shooting. The diaphragm device is fixed to the lens device.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

1: Aperture blade support tube (support member)
2: Diaphragm blade 3: Cam plate (cam member)
3a: cam groove 5: diaphragm blade 5a: rotation center pin (rotation center member)
5b: driving pin 5c: center of gravity 5d: locus of the center of gravity

Claims (7)

A plurality of aperture blades to which the rotation center member and the drive pin are fixed;
A support member that supports the rotation center member so that the diaphragm blades are rotatable;
A cam member having a cam groove with which the drive pin of the diaphragm blade engages;
In a diaphragm device comprising:
A predetermined direction is defined for the diaphragm device;
Each of the diaphragm blades
The locus of the center of gravity of the diaphragm blade when the diaphragm blade is driven does not intersect with a straight line that is parallel to the predetermined direction and passes through the rotation center of the diaphragm blade.
A diaphragm device characterized by that. The rotation center member is a pin protruding from the diaphragm blade,
The pin engages with a rotary bearing provided on the support member;
The diaphragm device according to claim 1. The support member has a projecting pin,
The rotation center member is a rotary bearing provided on the diaphragm blade,
Engaging the pin,
The diaphragm device according to claim 1. In order to adjust the amount of light passing through, further having the function of rotating the aperture blade further from the light amount adjustment region for adjusting the aperture diameter to make the aperture area zero,
The locus of the center of gravity when driving the diaphragm blades until the aperture area becomes zero outside the light amount adjustment region intersects with a straight line passing through the rotation center of the diaphragm blades in parallel with the predetermined direction,
The diaphragm apparatus according to any one of claims 1 to 3.   A lens apparatus comprising the diaphragm device according to any one of claims 1 to 4.   The said predetermined direction is a state parallel to the perpendicular direction when the said lens apparatus is used by a predetermined attitude | position in the state with which the said aperture device was mounted | worn with the said lens apparatus. Lens device.   An imaging apparatus comprising: the lens apparatus according to claim 5; and an imaging element that receives light from the lens apparatus.

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