JP4208619B2 - Aperture mechanism and lens device having a diaphragm mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aperture mechanism having means for preventing light leakage from a portion other than the effective aperture diameter determined by aperture blades , and a lens apparatus having an aperture mechanism.
[0002]
[Prior art]
Conventionally, in a diaphragm mechanism of a camera lens, as shown in FIGS. 7 to 9, the difference between the aperture diameter of the diaphragm and the outer diameter of the diaphragm blade determined by the diaphragm mechanism is other than the effective aperture diameter determined by the diaphragm blade. A diaphragm mechanism for a camera lens having a sufficient amount to prevent light leakage is known.
In Patent Document 1 or Patent Document 2, there is little difference between the aperture diameter of the aperture and the outer diameter of the aperture blade determined by the aperture mechanism, as shown in FIGS. 10 to 12, and the aperture determined by the aperture blade. In order to prevent light leakage other than the effective diameter, a camera lens having a second aperture blade that is arranged at a different location from the first aperture blade that determines the effective aperture diameter, and that is interlocked with the first aperture blade. The aperture mechanism is proposed.
[0003]
First, the conventional diaphragm mechanism shown in FIGS. 7 to 9 will be described.
As shown in FIGS. 7 to 9, a rotary shaft 51 called a fixed dowel is planted on each side of each of the plurality of diaphragm blades 50, and a pin 52 called a rotary dowel is planted on the other side. The rotary shafts 51 are inserted into the same number of the respective shaft holes 55 as the diaphragm blades 50 formed in a diaphragm blade container (provided with a circular opening 54 centered on the optical axis) 53 called a honeycomb. A plurality of diaphragm blades 50 are accommodated so as to be fitted.
Each pin 52 is fitted in each cam groove 58 formed in a cam member 56 (provided with a circular opening 57 centered on the optical axis) called a windmill. is doing.
[0004]
Then, by rotating the diaphragm blade container 53 and the cam member 56 relative to each other about the optical axis, the pins 52 move along the cam grooves 58, and the diaphragm blade container 53 and the cam member 56 are rotated. The plurality of diaphragm blades 50 accommodated between the cam members 56 are inclined with respect to the respective rotation shafts 51 and have an effective aperture diameter formed in the center portion by the overlapping of the inclined diaphragm blades 50. By changing the area, the light amount of the optical system required by the lens apparatus is adjusted.
In such a structure, when the diaphragm blade is narrowed down, the shape of the blade is determined so that light does not leak from a portion other than the effective diameter of the diaphragm, such as the shape of the curve 59 in the diaphragm blade (see FIG. 8). ) The shape of the diaphragm blade is dominantly determined by the curve 59 and the curve 60 which is a shape for determining the effective diameter of the diaphragm. The outer diameter shape of the diaphragm mechanism is determined in accordance with the diameter of the diaphragm blade thus determined.
However, if it is attempted to reduce the size and weight of the device itself by reducing the outer diameter of the lens housing, a sufficient difference in diameter between the curve 59 and the curve 60 cannot be ensured. The occurrence of non-matching parts causes light leakage from other than the effective aperture diameter.
[0005]
In such a case, as a diaphragm mechanism applied to a lens apparatus for the purpose of reducing the size and weight, FIGS. 10 and 11 (viewed in the direction of arrow D in FIG. 10) in FIG. 12 (a view taken in the direction of arrow E in FIG. 10), an effective diameter determining diaphragm blade group including a plurality of first aperture blades 61 for determining an effective aperture diameter, and an effective diameter determining diaphragm blade group An aperture mechanism for a camera lens, which is composed of a plurality of aperture blade groups for preventing light leakage, composed of a plurality of second aperture blades 66 for preventing light leakage from other than the effective diameter.
Since the structure using the second aperture blade is described in detail in Patent Document 1 or Patent Document 2, detailed description thereof is omitted.
[Patent Document 1]
Japanese Patent Application No. 2-242239 [Patent Document 2]
Japanese Patent Application No. 5-113591 [0006]
[Problems to be solved by the invention]
In the configuration of the diaphragm mechanism described in Patent Document 1 or Patent Document 2 described above, the second diaphragm blade 66 is provided to prevent light leakage that occurs when the first diaphragm blade 61 is narrowed as described above. However, the first wind turbine 62 for causing a predetermined inclination of the first aperture blade 61 and the second wind turbine 67 for generating an inclination for realizing the light leakage prevention operation of the second aperture blade are interlocked. Thus, the second diaphragm blade 66 must be driven, the mechanism for that is complicated, the number of parts increases, and the accuracy of parts becomes high. Etc. have problems.
[0007]
Therefore, the present invention does not require a configuration other than the diaphragm blades for generating the effective aperture diameter when downsizing the aperture mechanism, and can prevent the occurrence of light leakage from other than the effective aperture diameter. An object of the present invention is to provide a lens device having an aperture mechanism .
[0008]
[Means for Solving the Problems]
The diaphragm mechanism of the present invention is a diaphragm mechanism that houses the plurality of diaphragm blades and has a cylindrical housing member in which an opening is formed, and each of the plurality of diaphragm blades includes :
The circular arc-shaped portion, provided on the circular arc-shaped portion, when the narrowed down the plurality of diaphragm blades, a plurality of light-shielding protrusions for shielding light in the region of the aperture outside the effective diameter which is determined by the plurality of diaphragm blades And the housing member has a plurality of escape grooves ,
The plurality of light shielding protrusions shields a region where light leakage occurs outside the effective diameter of the diaphragm when the diaphragm blades are narrowed, and protrudes from the plurality of escape grooves to the outside of the diaphragm mechanism when the diaphragm blades are opened. It is characterized by.
The diaphragm mechanism of the present invention is characterized by having the diaphragm mechanism.
More specifically, the diaphragm mechanism of the present invention has a light-shielding projection that does not leak light when a group of diaphragm blades composed of a plurality of diaphragm blades moves to generate an effective aperture diameter. The light shielding protrusion has a shape protruding from a groove formed in a housing member that is a pedestal for storing the diaphragm blade when the diaphragm blade is opened, and the protruding light shielding protrusion is adjacent to the protrusion. The lens is arranged in an angular phase that does not interfere with an adjacent mechanism such as a lens driving mechanism.
[0009]
With such a configuration, the diaphragm blades that determine the effective diameter of the diaphragm are reduced in size, and in the stage where the diaphragm blades generate the effective diameter, light leakage due to the occurrence of a portion where the diaphragm blades do not overlap is determined. Without providing a diaphragm blade mechanism for light leakage separate from the diaphragm blade to be provided, by providing a projection that shields the necessary minimum area of the light leakage location, the entire diaphragm device can be reduced in size and the diaphragm mechanism element It is possible to realize a diaphragm mechanism that can be simultaneously simplified.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the following examples.
[0011]
【Example】
FIG. 1 is a longitudinal sectional view showing a diaphragm mechanism in an embodiment of the present invention, FIG. 2 is a view as seen from an arrow A in FIG. 1, and FIG. 3 is a view as seen from an arrow B in FIG.
In this embodiment, the effective diameter (D1) determining diaphragm blade group including a plurality of diaphragm blades 1 for determining the effective diaphragm diameter has a minimum necessary area for preventing light leakage from outside the effective diaphragm diameter. A light- shielding protrusion 2 that is a light leakage prevention protrusion is provided . The light-shielding projection 2 is formed from a cylindrical housing member 5 called a honeycomb in which the diaphragm blades are accommodated at an angle phase that does not interfere with an adjacent mechanism system when the diaphragm blade 1 is in the phase of the aperture opening diameter. It has a protruding configuration.
The number of diaphragm blades 1 (six in this embodiment) constituting the diaphragm blade group for determining a predetermined effective diameter is composed of an arc-shaped portion formed in an arc shape having a substantially constant width as a basic shape. Yes. The arcuate portion of the diaphragm blade 1 is provided with a light-shielding protrusion 2 for covering a region where the blades are not overlapped when the diaphragm blade 1 described later is narrowed.
[0012]
In the diaphragm blade 1, a fixed dowel 3 which is a center of rotation planted on one end side thereof is provided with a first shaft hole for the diaphragm blade 1 formed in the housing member 5 having a circular opening 5a in the center ( A rotating dowel 4 fitted to the diaphragm blade 1 is slidable in a cam groove 6b of a cam member 6 called a windmill having an opening 6a formed in the center. To fit.
Further, by rotating the cam member 6 with respect to the housing member 5 about the optical axis, the plurality of diaphragm blades 1 are tilted about the fixed dowel 3 and the predetermined diaphragm effective by the overlapping of the blades. The diameter is determined.
[0013]
By the way, the conventional diaphragm mechanism of FIG. 7 has a structure that can widen the outer width of the diaphragm blades, that is, a structure that can sufficiently secure a difference in diameter between a predetermined diaphragm effective diameter and the diameter of the lens device itself. If the aperture is narrowed, it overlaps with the tip side of the other diaphragm blades, thereby preventing light leakage between the other diaphragm blades.
However, in the structure in which the outer diameter of the diaphragm mechanism is reduced (smaller diameter) as shown in FIG. 10, the diameter of the diaphragm mechanism is reduced by forming the diaphragm blade into an arc shape with a substantially constant width. Therefore, when the diaphragm blades are narrowed down, a non-overlapping region is generated between the other diaphragm blades, resulting in light leakage.
[0014]
In order to prevent light leakage from the diaphragm blades having a reduced diameter as described above, a mechanism using a second diaphragm blade for preventing light leakage has been proposed in the past. Light leakage occurs from a non-overlapping region (the shaded area in FIG. 2) . In order to prevent this light leakage, in this embodiment , the light shielding protrusion 2 is formed only in a range in which the light leakage can be covered with a minimum area, thereby preventing light leakage when the aperture blade 1 is narrowed down. Is possible.
The light-shielding projection 2 has a structure that protrudes outside the diaphragm mechanism from the escape groove 5b formed in the housing member 5 when the diaphragm blade 1 is opened (see FIG. 3). Shielding protrusion 2, the cam ring 7 adjacent to the housing member 5 forming the stop mechanism as shown in FIG. 4, the fixed cylinder 8, so as not to interfere to any of the compensator 9, the light blocking projections for accommodation member 5 part 2 The amount of protrusion is determined.
[0015]
In particular, the compensator 9 has a structure in which the distance from the housing member 5 can be changed by a zoom operation. However, the higher the zoom magnification of the lens device in which the aperture device is incorporated, the smaller the distance between the compensator 9 and the housing member 5 tends to be. . At this time, the protrusion 9 a for fixing the roller 10 fitted and slid to the cam curve 7 a for performing a predetermined zooming operation on the cam ring 7 on the compensator 9 is the most with the housing member 5. It becomes a place where the interval is narrowed.
At this time, when the compensator 9 is moved to the telephoto side by a predetermined zooming operation, the projecting portion 9a is disposed on the housing member 5 as shown in FIG.
[0016]
As shown in FIG. 6, also in the arrangement of protrusions 9a on the compensator 9 enters on housing member 5, the angular phase arrangement as a collision raised portion 9a and the light-shielding protrusions 2 do not interfere, the restrictor blade 1 ( Or a light-shielding protrusion 2 ).
Therefore, according to the present embodiment, in the diaphragm blade 1 that determines the effective diameter of the diaphragm, only the area that prevents light leakage at the time of narrowing is shielded by projecting the light shielding protrusion 2, and the area other than the light shielding protrusion is blocked. By reducing the width on the base end side of the blade 1, it becomes possible to reduce the outer shape of the entire diaphragm mechanism.
At the same time, the light-shielding protrusion 2 that protrudes from the housing member 5 at the aperture opening diameter interferes with other mechanism systems arranged around the aperture mechanism, in particular, the zoom arrangement of the compensator 9 in the zoom mechanism unit. By being arranged at the angular phase that does not, it is possible to prevent light leakage and to form a diaphragm mechanism having a small diameter.
[0017]
The following embodiments can be listed as embodiments of the present invention.
Embodiment 1
In a diaphragm mechanism having a plurality of diaphragm blades and means for preventing light leakage from a portion other than the diaphragm effective diameter determined by the diaphragm blades,
The means for preventing light leakage covers a region where the diaphragm blades do not overlap when the diaphragm blades are narrowed down by the light leakage prevention protrusions provided on each of the plurality of diaphragm blades, and prevents exposure from the regions. A diaphragm mechanism characterized by being configured as follows.
Embodiment 2
The diaphragm mechanism according to the first embodiment, wherein the diaphragm blade is a diaphragm blade having a shape in which an outer diameter of the diaphragm blade determined by the diaphragm mechanism has a small diameter difference from a diaphragm opening diameter.
Embodiment 3
The diaphragm mechanism according to embodiment 1 or 2, wherein the light leakage prevention protrusions are arranged at an angular phase that does not interfere with an adjacent mechanism section when the diaphragm blades are opened.
[0018]
【The invention's effect】
According to the present invention, when downsizing the diaphragm mechanism, a diaphragm mechanism that does not require a configuration other than the diaphragm blades for generating the diaphragm effective diameter and can prevent light leakage from other than the diaphragm effective diameter , A lens device having an aperture mechanism can be realized.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view in an optical axis direction of a diaphragm mechanism in an embodiment of the present invention.
FIG. 2 is a view taken in the direction of arrow A in FIG.
FIG. 3 is a view taken in the direction of arrow B in FIG. 1;
FIG. 4 is a longitudinal sectional view in the optical axis direction showing a mechanism element adjacent to the diaphragm mechanism of the lens apparatus that constitutes the diaphragm mechanism in the embodiment of the present invention.
FIG. 5 is a longitudinal sectional view in the optical axis direction showing the mechanism arrangement on the zoom telephoto side of the mechanism of FIG. 4;
6 is a perspective view showing the structure of the aperture mechanism and its adjacent portion in FIG. 5. FIG.
FIG. 7 is a longitudinal sectional view of a conventional diaphragm mechanism in the optical axis direction.
8 is a view showing the diaphragm blades of FIG. 7;
9 is a view taken in the direction of arrow C in FIG.
FIG. 10 is a sectional view in the optical axis direction of a conventional diaphragm mechanism provided with another diaphragm blade mechanism for light shielding.
FIG. 11 is a view taken in the direction of arrow D in FIG.
12 is a view on arrow E in FIG.
[Explanation of symbols]
1, 50: Diaphragm blade 2: Light leakage prevention protrusion 3, 51: Fixed dowel 4, 52: Rotating dowel 5, 53: Honeycomb 5 a, 54: Honeycomb circular opening 6, 56: Windmill 6 a, 57: Windmill circular opening 7: Cam ring 7a: Cam curve 8: Fixed cylinder 9: Compensator 9a: Projection 10: Roller 55: Honeycomb shaft hole 58: Windmill cam groove 59, 60: (diaphragm blade) Curve 61: First diaphragm blade 62: First windmill 62a : First windmill opening 62b: First windmill cam groove 63: First diaphragm blade fixing dowel 64: First diaphragm blade rotating dowel 65: Common honeycomb 66: Second diaphragm blade 67: Second windmill 68: Second diaphragm blade fixed Dowel 69: Second aperture blade rotating dowel

Claims (3)

A plurality of aperture blades;
A diaphragm mechanism that houses the plurality of diaphragm blades and has a cylindrical housing member in which an opening is formed,
Each of the plurality of diaphragm blades,
And the circular arc-shaped portion,
A plurality of light-shielding protrusions that are provided in the arcuate part and shield light in a region outside the effective diameter of the diaphragm determined by the plurality of diaphragm blades when the plurality of diaphragm blades are narrowed down ;
The housing member has a plurality of relief grooves ;
The plurality of light shielding protrusions shields a region where light leakage occurs outside the effective diameter of the diaphragm when the diaphragm blades are narrowed, and protrudes from the plurality of escape grooves to the outside of the diaphragm mechanism when the diaphragm blades are opened. A diaphragm mechanism characterized by   The plurality of light shielding protrusions are provided at an angular phase at which the plurality of light shielding protrusions do not interfere with a mechanism part adjacent to the diaphragm mechanism when the plurality of diaphragm blades are opened. 2. The aperture mechanism according to 1. A lens apparatus comprising the aperture mechanism according to claim 1.

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