JP2000352736A - Diaphragm device for photographing lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make inexpensively realizable accurate control of transmissivity by using a high-accuracy and high-reliability ND filter capable of obtaining the transmissivitys in many stages. SOLUTION: This device 1 is equipped with a diaphragm blade moving on a plane orthogonal to the optical axis of a photographing lens and varying the diaphragm aperture, a diaphragm blade driving mechanism driving the diaphragm blade, the ND filter 24 moving on the plane orthogonal to the optical axis X-X of the photographing lens and varying transmitted light quantity, and an ND filter driving mechanism driving the ND filter 24. In such a case, the ND filter 24 is formed so that many dots 34 having the same density are formed on a transparent sheet 33 and the transmitted light quantity is changed in a moving direction stepwise or non-stepwise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel photographic lens aperture blade device. For more information, please refer to
The present invention relates to a technique for controlling an amount of transmitted light at low cost and with high accuracy in an aperture device having a D filter and moving an aperture blade and an ND filter by different driving means.

[0002]

2. Description of the Related Art A diaphragm device for a photographing lens such as a still camera or a video camera is provided with one type of "iris diaphragm" in which a plurality of diaphragm blades are rotated around an optical axis to adjust the diaphragm diameter. 2. Description of the Related Art An aperture device for a photographing lens, which is reduced in size, weight, and cost by using two aperture blades moving in opposite directions on a straight line, has come to be used.

However, if the aperture diameter becomes too small when the subject is bright, there is a problem that the image quality is deteriorated due to diffraction and dust is reflected due to an increase in the depth of focus.

Therefore, in order to suppress the deterioration of image quality due to diffraction, two aperture blades and an ND filter are provided. The aperture blade is driven by an aperture blade driving mechanism to form an aperture, and the ND filter is replaced with an ND filter. There is one that is driven by a driving mechanism to enter the aperture opening. Further, for example, as described in Japanese Patent Application No. 9-224788, there is a device in which an aperture blade driving mechanism and an ND filter driving mechanism are shared by one device.

[0005]

By the way, if the ND filter used in the conventional photographic lens aperture device can only enter and exit the aperture, then only one ND filter is required, and it can be constructed at low cost. However, there is a problem that the control of the amount of transmitted light becomes coarse.

As in the example shown in Japanese Patent Application No. 9-224788, when the transmittance of the ND filter needs to be controlled in multiple stages with the ND filter positioned at the aperture, a plurality of ND filters are required. In addition, there is a problem that a plurality of ND filters need to be accurately aligned and bonded to each other, which requires a high technology and is expensive.

In the case where a multi-stage transmittance is required, a large number of ND filters may be shifted and superimposed, or a density difference may be partially applied to a single ND filter by means of vapor deposition or the like. It is formed as an ND filter.

[0008] In the former case, if the sheets are overlaid, warping or peeling is likely to occur due to changes in temperature and humidity, and it is difficult to maintain reliability. Further, there is a problem that the thickness increases in the optical axis direction due to the overlapping, which hinders miniaturization.

In the latter case, although only one ND filter is required, there is a problem that the production process requires advanced technology, so that the yield is low and the cost is high.

Accordingly, an object of the present invention is to realize high-accuracy transmittance control at a low cost by using a highly accurate and highly reliable ND filter which can obtain multi-stage transmittance.

[0011]

According to the present invention, in order to achieve the above-mentioned object, a diaphragm apparatus for a photographing lens is provided with a plurality of halftone dots of the same density formed on a transparent sheet in a stepwise manner in the moving direction. It is formed such that the amount of transmitted light changes stepwise or steplessly.

Therefore, in the photographic lens diaphragm apparatus of the present invention, since the halftone dots may be of a single density, an ND filter can be formed in a single film forming step, and an inexpensive and highly accurate ND filter can be formed. Can be obtained.

According to another aspect of the present invention, in order to solve the above problem, an ND filter is formed by forming a film having the same concentration on a transparent sheet and forming a large number of halftone dots in the film. Is formed so that the amount of transmitted light changes stepwise or steplessly in the moving direction.

Therefore, in another photographic lens aperture device of the present invention, when forming the ND filter, first,
It is sufficient to form a film of a single concentration, and a single film forming process is sufficient, and an inexpensive and highly accurate ND filter can be obtained.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a photographic lens diaphragm apparatus according to an embodiment of the present invention.

As shown in FIG. 1, an aperture device 1 for a photographing lens forms a vertically long rectangle as viewed from the optical axis XX and is orthogonal to the optical axis in a housing 2 which is flat in the optical axis direction. 2 movably provided in the direction (in this embodiment, the vertical direction).
A plurality of diaphragm blades 3, 4; a diaphragm blade driving mechanism 5 for driving the diaphragm blades 3, 4;
An ND filter member 6 provided movably in the same direction as 4 and an ND filter driving mechanism 7 for driving the ND filter member 6 are provided.

The housing 2 has a rear plate 9 and a front plate 10 which are connected to each other with a middle plate 8 interposed therebetween. The rear plate 9 has a shallow box shape that opens forward, and a circular light passage hole 11 is formed in the center of the rear plate 9.
Two support pins 12, 12,. A circular light passage hole 13 is formed in the center of the front plate 10, and the light passage hole 13 is aligned with the center of the light passage hole 11 of the rear plate 9.

One of the aperture blades 3 is substantially J-shaped when viewed from the front, and has a notch 14 opened upward. The aperture blade 3 has one on the left side and two
Guided slits 15, 15, 15 extending vertically
Are formed, and a connection slit 16 extending in the left-right direction is formed at the upper right end. The support pins 12, 1 of the rear plate 9 are provided in the guided slits 15, 15, 15, respectively.
2 and 12 are slidably inserted, whereby the diaphragm blade 3 is supported by the rear plate 9 so as to be vertically movable.

The other diaphragm blade 4 is substantially h-shaped when viewed from the front, and has a notch 17 opened downward. The aperture blade 4 has two vertically aligned left and right wings, and one
Guided slits 18, 18, 18 extending vertically
Are formed, and a connection slit 19 extending in the left-right direction is formed at the upper left end. The support pins 12, 1 of the rear plate 9 are provided in the guided slits 18, 18, 18, respectively.
The aperture blades 2 and 12 are slidably inserted, whereby the diaphragm blade 4 is supported by the rear plate 9 so as to be movable in the vertical direction.

The apertures 20 are formed by the cutouts 14 and 17 of the aperture blades 3 and 4 which are overlapped with each other.

The middle plate 8 has a substantially square shape when viewed in the optical axis direction, a circular light passage hole 21 is formed at the center, and mounting holes 22, 22,... Are formed at substantially four corners. ing.
The rear plate 9 is provided in the mounting holes 22, 22,.
Are press-fitted to the middle, whereby the middle plate 8 is supported by the rear plate 9 and the front plate 10 is attached so as to close the front side of the rear plate 9. A moving space for the diaphragm blades 3 and 4 is formed on the rear side with the middle plate 8 interposed therebetween, and a moving space for the ND filter member 6 is formed on the front side. The light insertion holes 11, 13 and 21 formed in the rear plate 9, the front plate 10 and the middle plate 8, respectively, overlap in the front-rear direction, and the central axis thereof coincides with the optical axis XX.

The ND filter member 6 includes a filter holding plate 23
And an ND filter 24 held therein. The filter holding plate 23 has an inverted-h shape when viewed from the front, has a substantially U-shaped notch 23a opened upward, and an ND filter 24 is attached so as to cover the notch 23a. Guide slits 25, 25 extending in the vertical direction are formed on both left and right edges of the filter holding plate 23, and a connecting slit 26 extending in the horizontal direction is formed at the lower left end. The ND filter member 6 is provided between the middle plate 8 and the front plate 10 in the guided slits 25 of the filter holding plate 23 and the rear plate 9.
Are slidably inserted through the support pins 12, 12,.
As a result, the ND filter member 6 is supported by the rear plate 9 so as to be vertically movable.

The diaphragm blade driving mechanism 5 comprises a motor 27 fixed to the upper rear surface of the housing 2 and a rotating arm 28 fixed to an output shaft of the motor 27. Connecting pins are provided at both ends of the rotating arm 28. 29, 29 are protruded forward.

Arc-shaped slits 9a, 9a are formed on the left and right sides of the upper end of the rear plate 9 of the housing 2. The slits 9a, 9a are formed in an arc shape about the output shaft of the motor 27, and the connecting pins 29, 29 are inserted through the slits 9a, 9a, and the connecting pins 29, 29
Are slidably connected to the connection slits 16 and 19 of the aperture blades 3 and 4.

When the motor 27 is driven, the turning arm 28 is turned, thereby connecting the connecting pin 29,
As one of the apertures 29 rises (or descends) and the other descends (or rises), the diaphragm blades 3 and 4 are moved in the vertical direction and in the directions opposite to each other. Aperture opening 2 formed by notches 14, 17
The diameter of 0 is changed.

The ND filter driving mechanism comprises a motor 30 fixed to the lower rear surface of the housing 2 and a turning arm 31 having one end fixed to an output shaft of the motor 30. At the end, a connecting pin 32 is provided to protrude forward.

An arc-shaped slit 9b is formed on the left side of the lower end of the rear plate 9 of the housing 2. The slit 9b is formed in an arc shape centered on the output shaft of the motor 30. The connection pin 32 is inserted through the slit 9b, and the connection pin 32 slides on the connection slit 26 of the ND filter member 6. It is movably connected.

When the motor 30 is driven, the turning arm 31 is turned, and the connecting pin 32 is thereby turned.
Moves in the vertical direction, so that the ND filter member 6 is moved in the vertical direction.

As described above, by driving the aperture blade driving mechanism 5 and the ND filter driving mechanism 7 separately,
By changing the size of the aperture 20 and defining the positional relationship of the ND filter 24 with respect to the aperture 20, the amount of light transmitted through the aperture 20 is controlled.

The ND filter 24 is characterized in the present invention.

FIG. 2 is an enlarged front view showing the ND filter 24. The ND filter 24 is formed by forming single-density films 34, 34,... In a halftone dot shape on a transparent sheet 33 by a general printing process of vapor deposition or photolithography. In this case, the dot-like films 34, 34,... Are formed according to a certain rule by a method similar to the so-called “dot printing”. N moved by the ND filter driving mechanism 7
The position of the D filter 24 with respect to the aperture 20 changes, for example, as shown in FIGS. 2A to 2E (note that the circle indicating the aperture 20 is shown for convenience, and is not drawn on the ND filter 24). ). Thereby, the aperture opening 2
The amount of light passing through 0, that is, the transmittance can be changed stepwise. For example, the transmittance reaches 100% in the case of “a”, the transmittance inherent in the films 34, 34,... In the case of “e”, and the transmittance changes stepwise in the middle (b to c to d).

FIG. 2 shows halftone dots 34, 3
Although the size is sequentially changed according to the rule of keeping the pitch of 4,..., Many modified examples are conceivable. For example, the dot 24A shown in FIG.
The forming pitch is changed while keeping the size of 34,... Constant, and a dot 24B shown in FIG. 4 is obtained by arranging halftone dots 34, 34,. It is. Of course, various other rules for the arrangement of the dots 34, 34,... Can be considered.

Further, as shown in FIG.
The same purpose can be achieved by forming a film 35 of equal concentration uniformly on the transparent sheet 33 and forming holes 36, 36,... At positions corresponding to the positions of the halftone dots of each pattern described above. Can be achieved. In this case, the hole 3
Instead of actually drilling the holes 6, 36,..., The portions corresponding to the holes 36, 36,. You may do it.

In the photographic lens aperture device 1 described above, although a single-density film is used,
It is possible to obtain an ND filter having the same multi-stage transmittance as when a multi-concentration film is used. Therefore, an ND filter can be formed in a single film forming step or a single perforation step, and an inexpensive and highly accurate ND filter can be obtained.

Further, since there is no need to provide a density difference in multiple stages, a high-precision deposition technique or printing technique is not required, and an ND filter can be obtained at a low cost in this respect as well.

Further, when a multi-stage transmittance is required, it is not necessary to shift and stack a large number of ND filters as in the prior art, so that the material cost is small and the number of processing steps is small. Extremely inexpensive.

Furthermore, unlike the case where a large number of ND filters are stacked and bonded, there is no fear of warping or peeling due to a change in temperature and humidity, so that the reliability is high.

It should be noted that the shapes and structures of the respective parts shown in the above-described embodiments are merely examples of the specific embodiments to be carried out when carrying out the present invention, and the technical scope of the present invention is thereby reduced. It should not be interpreted restrictively.

[0039]

As is apparent from the above description, the present invention provides a diaphragm apparatus for a photographing lens which moves on a plane perpendicular to the optical axis of the photographing lens to change the diaphragm aperture, and the diaphragm blade. Blade drive mechanism for driving the lens, an ND filter that moves on a plane orthogonal to the optical axis of the taking lens to vary the amount of transmitted light, and an ND filter drive mechanism that drives the ND filter The apparatus is characterized in that the ND filter is formed such that a number of halftone dots having the same density are formed on a transparent sheet so that the amount of transmitted light changes stepwise or steplessly in the moving direction.

Therefore, in the aperture device of the photographic lens of the present invention, since the halftone dots may be of a single density, an ND filter can be formed in a single film forming step, and an inexpensive and highly accurate ND filter can be formed. Can be obtained.

Further, another aperture device for a photographing lens according to the present invention includes an aperture blade that moves on a plane orthogonal to the optical axis of the imaging lens to vary the aperture, an aperture blade driving mechanism that drives the aperture blade, In an aperture device for a photographing lens, comprising: an ND filter that moves on a plane orthogonal to the optical axis of the photographing lens to vary the amount of transmitted light; and an ND filter driving mechanism that drives the ND filter. A film having the same concentration is formed on a simple sheet, and a number of holes are formed in the film in a halftone dot shape so that the amount of transmitted light changes stepwise or steplessly in the moving direction. I do.

Accordingly, in another photographic lens aperture device of the present invention, when forming the ND filter, first,
It is sufficient to form a film of a single concentration, and a single film forming process is sufficient, and an inexpensive and highly accurate ND filter can be obtained.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a photographic lens aperture device according to the present invention, which is an exploded perspective view.

FIG. 2 is an enlarged front view showing an ND filter.

FIG. 3 is an enlarged front view showing a modified example of the ND filter.

FIG. 4 is an enlarged front view showing another modified example of the ND filter.

FIG. 5 is an enlarged front view showing still another modified example of the ND filter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Aperture device of photographing lens, 3 ... Aperture blade, 4 ... Aperture blade, 5 ... Aperture blade drive mechanism, 7 ... ND filter drive mechanism, 20 ... Aperture aperture, 24 ... ND filter, 33 ... Transparent sheet, 34 ... Net Point, 24A ... ND filter, 24B ...
ND filter, 24C ND filter, 35 membrane, 36
... holes, XX ... optical axis

Claims (2)

[Claims] An aperture blade that moves on a plane orthogonal to the optical axis of the photographing lens to vary the aperture, an aperture blade driving mechanism that drives the aperture blade, and a plane that is orthogonal to the optical axis of the photographing lens. An ND filter that moves to vary the amount of transmitted light;
An aperture device for a photographing lens provided with an ND filter driving mechanism for driving said ND filter, wherein said ND filter is formed stepwise or steplessly in a moving direction by forming a number of halftone dots of the same density on a transparent sheet. A diaphragm device for a photographing lens, wherein the diaphragm is formed so that the amount of transmitted light changes. 2. A diaphragm blade that moves on a plane orthogonal to the optical axis of the photographing lens to vary the aperture, a diaphragm driving mechanism that drives the diaphragm blade, and a plane that intersects perpendicularly with the optical axis of the photographing lens. An ND filter that moves to vary the amount of transmitted light;
An aperture device for a photographing lens having an ND filter driving mechanism for driving the ND filter, wherein the ND filter is formed by forming a film of the same density on a transparent sheet and forming a large number of halftone dots in the film. An aperture unit for a photographing lens, wherein the transmitted light amount is changed stepwise or steplessly in the moving direction.