JP2575871Y2 - Iris device for interchangeable lenses - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm device for an interchangeable photographic lens.

[0002]

2. Description of the Related Art A conventional diaphragm apparatus for a photographic interchangeable lens has a structure as shown in FIG. The example shown in FIG. 3 is for a zoom lens in which both the aperture diameter and the aperture position change in conjunction with zooming.
In the drawing, reference numeral 1 denotes an aperture blade, a predetermined number of which are combined, each of which has a pin 1b inserted into a hole of a fixed ring (not shown) and a pin 1a inserted into a cam groove 2a of an aperture blade drive plate 2. Is provided. The aperture blade driving plate 2 is rotatable around the optical axis and has a projection 2b on the outer periphery.

As shown by a solid line C in FIG. 4, the shape of the cam groove 2a of the diaphragm blade driving plate 2 is such that the first diaphragm stop lever 3, which is provided later, in the region x near the first stage of diaphragm stop changes with the change in the number of diaphragm stages. The first stop lever 3 is displaced isosterially with respect to the change in the number of steps in the area y after that, and at the boundary between the area near the first step and the area thereafter. The aperture lever is determined so as to be smoothly displaced, and this boundary point is set so as to be near one aperture stage.

The first stop lever 3 is engaged with an aperture setting lever 4 on the camera side, and has a disk portion 3a (partially omitted in FIG. 3). The disk portion 3a is mounted on a fixed lens barrel (not shown). It is supported rotatably around the optical axis. The first aperture lever 3 has a transmission pin 5 and is urged downward by a spring 6 in the drawing. The second squeezing lever 7 is provided rotatably about a shaft 8, has an arm 9 extending at one end in the optical axis direction, has a groove 7 a into which the transmission pin 5 is fitted, and is provided with a spring 6. It is urged upward by a spring 10 having a small force, that is, clockwise. The arm 9 is formed with an inclined groove 9a that engages with the projection 2b of the diaphragm blade driving plate 2, and a slope surface 9b having a height gradient of γ with respect to the stroke L in the optical axis direction.

A lens unit (not shown) is provided with a diaphragm unit including a diaphragm blade 1 and a diaphragm blade driving plate 2.
Numeral 1 slides in parallel with the optical axis by zooming together with the lens group and the aperture unit. The protrusion 11 is in contact with the inclined surface 9b. 3 shows a state in which the zoom lens is at the telephoto position. The transmission pin 5 is located at the lowest point of the groove 7a of the second aperture lever 7.

When an aperture value for obtaining an appropriate exposure based on subject brightness, shutter speed, film sensitivity, and the like is determined by a photometric circuit or the like of a camera at the time of photographing, the diaphragm is stopped by an amount corresponding to the value immediately before the front curtain of the shutter runs. When the setting lever 4 moves downward (in the direction of the arrow) in the figure, the first aperture lever 3 rotates counterclockwise around the optical axis by the spring 6,
At the same time, the second narrowing lever 7 is moved through the pin 5 and the groove 7a.
Since the arm 9 also rotates in the same direction with the arm 9, the diaphragm driving plate 2 rotates counterclockwise by a predetermined amount via the inclined groove 9a and the projection 2b, and the diaphragm blade 1 is narrowed. At this time, the relationship between the stroke of the first aperture lever 3 and the number of aperture steps is shown in FIG.
In accordance with the reference setting curve of solid line C shown in FIG.

Next, when a lens group (not shown) is moved to a wide-angle position, the diaphragm blade 1, the diaphragm blade driving plate 2, and the projection 1 are moved.
1 slide together by a distance L to the right in the figure. Accordingly, the diaphragm blade driving plate 2 rotates counterclockwise by the sum of the inclination of the inclined groove 9a and the gradient γ of the gradient surface 9b, and the pin 1a of the diaphragm blade moves along the cam groove 2a, and the diameter of the diaphragm becomes smaller. Changes,
As it becomes smaller, the pin 5 is located at the highest point of the groove 7a.

As described above, the diaphragm blade driving plate 2 is rotated by the sum of the inclination of the inclined groove 9a and the gradient γ of the inclined surface 9b in accordance with the movement of the lens group, thereby changing the aperture diameter. Thus, the open F value is kept constant regardless of the position of the lens group.

When the aperture setting lever 4 moves downward in the figure at this position, the pin 5 moves from the uppermost point of the groove 7a to the lowermost point by the rotation of the first aperture lever 3 in the initial stage,
Thereafter, the second aperture lever 7 and the arm 9 are displaced to rotate the aperture blade drive plate 2 and operate the aperture blade 1. Here, assuming that the stroke of the first aperture lever 3 corresponding to the moving distance of the pin 5 in the groove 7a is δ, the relationship between the stroke of the first aperture lever 3 and the number of aperture steps is as shown in FIG. The first and second squeezing levers are in the initial stage δ
Since it is not involved in the actual aperture stop, it becomes like a broken line C ', and the error at one or more stops of the aperture at the time of wide-angle shooting is eliminated.

By the way, if the above-mentioned stroke δ is not provided at the time of wide angle, when the diaphragm is at the telephoto position as shown in FIG. 5, the relationship between the number of diaphragm steps and the stroke of the first diaphragm lever 3 is as shown by a solid line C. Although it will be as the reference setting curve, if the aperture moves to the wide angle position due to zooming,
With this movement, the diaphragm blade driving plate 2 rotates, and the pin 1a of the diaphragm blade 1 slides in the cam groove 2a. Therefore, the relationship between the number of diaphragm steps and the stroke of the first diaphragm lever 3 is represented by a two-dot chain line C ". Then, for example, when this lens is mounted on a camera with a shutter-priority automatic iris and an image is taken, in order to obtain a proper exposure, the aperture is measured by the photometry circuit so that the iris is set to 2
When instructing to stop down by a step, the aperture setting lever 4 of the camera body stops at a position where the first aperture stop lever 3 of the lens moves by a stroke a. At this time, at the telephoto position (TELE) of the lens, the first aperture
The aperture value becomes an appropriate value after being stopped down, but at the wide-angle position (WIDE), an error △ ₁ occurs and the aperture is stopped down too much.

[0011]

In the prior art as described above, after one stage of narrowing down, as shown in FIG.
Although it is possible to eliminate the error from the reference setting curve, there is a problem that the error occurs, for example, as indicated by # ₂ and # _{3 in} FIG.

The present invention has been made in view of such a conventional problem. In the vicinity of the first stop of the stop, the first stop lever 3 is displaced in an equal ratio with respect to a change in the number of stops. The error from the reference setting curve in any state of zooming or focusing without changing the conventional aperture control system between the camera body and the interchangeable lens, which is based on the principle that the first aperture lever is displaced in an equal manner. It is an object of the present invention to provide an aperture device for an interchangeable lens which does not cause the problem.

[0013]

According to the present invention, an aperture blade 1 is provided.
A first aperture lever 3 interlocked with the aperture setting lever 4, a second aperture lever 7, 9 interlocked with the first aperture lever 3, and an aperture interlocked with the second aperture lever 7, 9. A blade drive member 2 and the aperture blade drive member 2
The diaphragm blade 1 is actuated by the rotation, and the second rotation with respect to the set number of diaphragm stages is performed.
First cam means 2 having a cam portion 2a formed so that the displacement amount of the narrowing levers 7 and 9 of the first cam member 2 varies in an equal manner.
a, 1a and 1b, and a guide portion 9a for moving the diaphragm blade driving member 2 straight and rotating in conjunction with the lens moving operation, and the rotation of the diaphragm blade driving member 2 causes the first cam means to rotate. Open F value correction means 2b and 9a for operating the apertures 2a, 1a and 1b to correct the aperture opening and to keep the open F value constant; the first aperture lever 3 and the second aperture levers 7 and 9;
And the amount of displacement of the first aperture lever 3 with respect to the number of aperture stages is changed in an area near the first stage of the number of aperture stages in conjunction with the isometric change of the amount of displacement of the second aperture lever with respect to the number of aperture stages. The aperture device for an interchangeable lens is characterized in that it has conversion means 3b and 13 for controlling so as to change it in an isometric manner and to change it in a larger area thereafter. Further, by embodying the configuration of the first invention, the conversion means 3b and 13 are provided on the second cam means 3b provided on the first aperture lever 3 and on the second aperture levers 7 and 9 respectively. The diaphragm device for an interchangeable lens according to claim 1, further comprising an engaging portion 13 engageable with the second cam means 3b.

[0014]

According to the first aspect of the present invention, the amount of displacement of the second aperture lever with respect to the number of aperture steps varies in an equal manner. The isometric change of the second aperture lever with respect to the number of aperture stages is caused by the conversion means to change the amount of displacement of the first aperture lever with respect to the number of aperture stages in an area corresponding to the vicinity of the first stage of aperture reduction, and in the subsequent areas. Then it is changed isosterically.
The invention of claim 2 embodies the invention of claim 1, and the isometric change of the second aperture lever and the isometric change of the first aperture lever are related to the second cam means 3b. This is provided by engagement with the engageable engagement portion 13.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a zoom lens in which both the aperture diameter and the aperture position change in conjunction with zooming in one embodiment of the present invention, and FIG. 2 shows the stroke of the aperture stop lever and the number of aperture steps in the embodiment. FIG.

A predetermined number of diaphragm blades 1 are combined,
Each of them has a pin 1b fitted in a hole of a fixed ring (not shown).
And a pin 1a fitted into the cam groove 2a of the aperture blade driving plate 2.
Are provided. The aperture blade driving plate 2 is rotatable around the optical axis and has a projection 2b on the outer periphery. The shape of the cam groove 2a of the aperture blade drive plate 2 is the second shape as shown by the solid line D in FIG.
Is formed so that the number of aperture stages changes in an equal manner with respect to the stroke of the aperture lever 7.

The first stop lever 3 is engaged with the stop setting lever 4 on the camera side, and has a disk portion 3a (partially omitted in FIG. 1). It is supported rotatably about the axis. The first aperture lever 3 has a cam portion 3b, and is urged downward by a spring 6 in the drawing. The second aperture lever 7 is provided rotatably about an axis 8 and has an arm 9 extending at one end in the optical axis direction.
And has a pin 13 engageable with the cam portion 3b, and is urged downward by the spring 12 in the figure, that is, counterclockwise. The pin 13 is always in contact with the cam portion 3b. The arm 9 is formed with an inclined groove 9 a that engages with the projection 2 b of the diaphragm blade drive plate 2.

Next, the operation will be described. When an aperture value for obtaining an appropriate exposure based on the subject brightness, shutter speed, film sensitivity, and the like is determined by a photometric circuit or the like of the camera at the time of photographing, the aperture setting lever 4 is adjusted by an amount corresponding to the value immediately before the front curtain of the shutter runs. Moves downward in the drawing, the first aperture lever 3 is rotated counterclockwise around the optical axis by the spring 6, and at the same time, the second aperture lever 7 also moves the arm 9 through the cam portion 3 b and the pin 13. Accordingly, the diaphragm driving plate 2 rotates counterclockwise by a predetermined amount via the inclined groove 9a and the projection 2b, and the diaphragm blade 1 is narrowed. At this time, the relationship between the stroke of the first aperture lever 3 and the number of aperture steps follows the reference setting curve indicated by the solid line C shown in FIG.

Next, when a lens group (not shown) is moved to a wide-angle position, the diaphragm blade 1, the diaphragm blade driving plate 2 and the projection 1 are moved.
1 slide together by a distance L to the right in the figure. Accordingly, the diaphragm blade driving plate 2 rotates counterclockwise by the amount of the inclination of the inclined groove 9a, and the pin 1a of the diaphragm blade moves along the cam groove 2a, and the diaphragm diameter changes and becomes smaller.

Next, the conversion to the reference setting curve showing the relationship between the stroke of the first aperture stop lever 3 and the number of aperture steps will be described. In FIG. 2, a line D indicates the relationship between the stroke of the second aperture lever 7 and the number of aperture steps. That is, the displacement amount of the second aperture lever 7 with respect to the number of aperture stages changes in an equal manner, and the line D is determined by the shape of the cam groove 2a.

A line C is a reference setting curve determined based on the conventional aperture control system between the camera body and the interchangeable lens, and shows the relationship between the stroke of the first aperture lever 3 and the number of aperture steps. The shape of the cam portion 3b is
It is determined that the stroke of the second aperture lever 7 corresponding to an arbitrary number of aperture stages in the line D in FIG. 2 is converted into the stroke of the first aperture lever 3 corresponding to the same number of aperture stages in the line C. For example, it is determined that a stroke x 'corresponding to one reduction stage in the drawing is converted into x and a stroke y' corresponding to three reduction stages in y is converted into y.

With the above-described configuration, without changing the conventional aperture control system between the camera body and the interchangeable lens, the stroke and the number of aperture steps of the first aperture lever before the first aperture stop, which have conventionally been problems, have been problematic. The error with respect to the reference setting curve in the relationship is determined by the telephoto position (TEL) of the lens.
E), and can be resolved regardless of the wide-angle position (WIDE). This is because the amount of displacement of the second aperture lever 7 with respect to the number of aperture steps changes in an equal manner, and the aperture blade driving plate 2 rotates during zooming or focusing, and the pin 1a of the aperture blade 1 connects the cam groove 2a. Even if it slides, no error occurs in the relationship between the stroke of the second aperture lever 7 and the number of aperture steps (line D).

The points to be noted in this embodiment are as follows. That is, an isometric change in the displacement of the second aperture lever 7 with respect to the number of aperture stages is determined by the first aperture lever 3.
Is to convert the displacement amount into the isometric change in the area corresponding to the vicinity of the first stage of the narrowing down of the displacement amount with respect to the number of steps of the narrowing down of the first narrowing down lever 3, and to the isometric change in the area thereafter. .

As described above, in an interchangeable lens that changes the aperture diameter with a lens moving operation such as zooming or focusing and maintains a constant open F value, such as a zoom lens or a macro lens, the operation of the aperture blade driving member And the conversion means (the cam portion 3b of the stop-down lever 3 and the pin 13 of the stop-down lever 7) set by the cam means so that the amount of displacement with respect to the number of stops is changed in an equal manner. A standard in a conventional aperture control system in which the amount of displacement with respect to the number of aperture steps interlocking with the isometric change changes isometrically in a region corresponding to the vicinity of the first stage of the aperture stop, and changes isometrically in a region after that. An aperture device having a first aperture lever engaged with the body-side aperture setting lever set according to the setting curve can be constructed.

[0025]

According to the first aspect of the present invention, the amount of displacement of the second aperture lever with respect to the number of aperture steps changes in an equal manner, so that the aperture blade driving plate rotates during zooming or focusing, and the pin of the aperture blade is rotated. Even if you slide the cam groove,
There is no error in the relationship between the stroke of the second aperture lever and the number of aperture stages. The isometric change of the displacement amount of the second aperture lever with respect to the number of aperture stages is equivalently changed by the conversion means in the region corresponding to the vicinity of the first stage of aperture reduction with respect to the aperture amount of the first aperture lever,
In the subsequent region, the aperture can be changed isotropically, so that there is no need to change the conventional aperture control system between the camera body and the interchangeable lens. As it is, it is possible to eliminate an error with respect to the reference setting curve in the relationship between the stroke of the first aperture stop lever and the number of aperture steps before the first aperture stop. A second aspect of the present invention embodies the idea of the first aspect, wherein the isotropic change of the second aperture lever and the isometric change of the first aperture lever are the second cam. The effect brought about by the engagement of the engaging portion 13 engageable with the means 3b is essentially the same as the effect according to the first aspect.

[Brief description of the drawings]

FIG. 1 is a perspective view of one embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a stroke of a stop-down lever and the number of steps of the stop according to the embodiment.

FIG. 3 is a perspective view of a conventional example.

FIG. 4 is a diagram illustrating a relationship between a stroke of a stop-down lever and the number of stops in a conventional example.

FIG. 5 is a diagram showing the relationship between the stroke of the stop-down lever and the number of stops in the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 diaphragm blade 2 diaphragm blade drive plate 2a cam groove 3 first diaphragm lever 3b cam portion 7 second diaphragm lever 9 arm 12 spring 13 pin In the drawings, the same or corresponding parts are denoted by the same reference numerals.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-143728 (JP, A) JP-A-60-35717 (JP, A) JP-A-61-102637 (JP, A) 78008 (JP, U) Japanese Utility Model Showa 57-54121 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03B 9/00-9/07

Claims (2)

(57) [Scope of request for utility model registration] An aperture blade, a first aperture lever interlocked with an aperture setting lever, a second aperture lever interlocked with the first aperture lever, and an aperture blade drive interlocked with the second aperture lever and the member is rotatable in response to operation of the restrictor blade driving member actuates the restrictor blade by the pivoting, said second relative set aperture number
Shape as the displacement amount of the narrowing lever varies arithmetically
A first cam means having made the cam unit, in conjunction with the lens moving operation is straight and rotate the diaphragm blade driving member
A guide portion, which is rotated by the rotation of the diaphragm blade driving member.
An open F value correction means for operating the first cam means to correct the aperture opening and to keep the open F value constant; and installed between the first aperture lever and the second aperture lever. In conjunction with the isometric change of the displacement amount of the second aperture lever with respect to the number of aperture stages, the displacement amount of the first aperture lever with respect to the number of aperture stages is changed proportionally in an area near the first stage of the number of aperture stages. And a conversion means for controlling so as to change the difference in a larger area thereafter. 2. The conversion means is provided with a second cam means provided on the first aperture lever and an engagement provided on the second aperture lever and engageable with the second cam means. The diaphragm device for an interchangeable lens according to claim 1, further comprising a unit.