JPS6035717A - Control device for aperture of zoom lens - Google Patents

Abstract

PURPOSE:To correct fluctuation in an aperture value by having a driving part which is formed on a moving member moving in accordance with a zoom operation and an aperture operating plate which moves in one body with the moving member, is freely rotatable with respect to the fixing part of a lens barrel and has an engaging part. CONSTITUTION:A rotary lens barrel 2 is freely rotatably fitted to the inside of a stationary lens barrel 1. Rectilinear lens barrels 3, 4 are freely slidably fitted to the inside of the barrel 2 and an arm 3a as a driving part extends from the barrel 3 to the outside in the radial direction. An aperture operating plate 10 is freely rotatable with respect to the barrel 1. The aperture is open and shut by the relative rotation of the plate 10 and a holding plate 14. In such a constitution, the fluctuation in the aperture value owing to zooming is corrected.

Description

TECHNICAL FIELD The present invention relates to a device for correcting variations in aperture value that occur when the focal length of a zoom lens is changed.

When performing zooming in a conventional zoom lens, if the focal length changes, the actual aperture value may change accordingly, and the brightness of the lens may change. Fluctuations in the aperture value (changes in lens brightness) during actual use can make the lens less convenient to use.
In the past, various proposals have been made to provide such zoom lenses with correction devices that correct the aperture diameter during zooming so that the same aperture value is always obtained.

However, all of the conventional proposals require a large number of members such as cam portions and rings, making the mechanism extremely complicated. Therefore, the operation of these mechanisms and their operations become heavier, and the shocks and the like during operation become more difficult.

Furthermore, the manufacturing process is time-consuming and the reliability of the product is reduced. In addition, a large number of parts are arranged and space is required for them to operate, which increases the size of the lens, but this goes against the recent demand for smaller lenses. It's not a good thing.

OBJECT It is an object of the present invention to provide an aperture control device that can correct variations in aperture value due to zooming with an extremely simple configuration.

SUMMARY OF THE INVENTION The present invention provides a driving part in a member that moves by a zoom operation, and a cam part in an operating member to which an aperture lever that performs a narrowing operation is pivotally attached, and the driving part and the cam part engage with each other, and the zoom The present invention is characterized in that when the drive unit is moved by operation, the actuating member is driven and the aperture lever is displaced.

Example Next, one embodiment of the present invention will be described with reference to the accompanying drawings.

1 and 2 show one embodiment of the present invention, and FIG. 1 shows a longitudinal section of an interchangeable lens for a camera. 1st
In the figure, (5) is a mounting lens barrel, which has a mount portion for mounting an interchangeable lens on the camera body. (
1) is a fixed lens barrel and is fixed to the lens barrel (5). The fixed lens barrel (1) is formed with a rectilinear groove (1aX1b) extending in a direction parallel to the optical axis (hereinafter simply referred to as the optical axis) of a lens to be attached.

A rotating lens barrel (2) is rotatably fitted inside the fixed lens barrel (1), and the rotating lens barrel (2) has a cam groove (2a).
)(2b) is formed. It also has a zoom ring (2c) that extends outward in the radial direction from the rotating lens barrel (2) and protrudes outward through an opening formed in the fixed lens barrel (1).

A linear lens barrel (31 (41) is slidably fitted inside the rotating lens barrel (2), and bottles (3bX4a) are arranged radially outward from the linear lens barrel (3) (4). stretch,
The pin (3b) is fitted into the straight groove (1a) of the cam groove (2a), and the pin (4a) is fitted into the straight groove (1b) of the cam groove (2b). Further, the rectilinear lens barrel (3) holds a lens group (L) including a diaphragm device. Furthermore, an arm (3a) extends radially outward from the rectilinear lens barrel (3).

(jl) is the aperture blade and the holding plate (I4) and the aperture operation plate (1
0) The pin held between K and implanted in the aperture blade (11) is pivotally attached to the holding plate (14J), and the pin is attached to the aperture operation plate (14J).
o) The upper bottle fits into a cam groove formed in the aperture blade (11), and the aperture operation plate (10) and holding plate (14) rotate relative to each other, thereby opening and closing the aperture.

The fringe operation plate (10) has a donut-shaped ring that extends to the rear of the lens (to the right in Figure 1 and downward in Figure 2), is bent further, and has a radius (7) centered on the optical axis. , is held so as to rotate around the optical axis. Further, a cam plate (7ia) extends from the operating ring (7) in a direction parallel to the optical axis, and an aperture correction cam (7C) is formed on the cam plate (7a). is the open correction cam (
7b). The arm (3a) extending from the linear lens barrel (3) is fitted into the aperture correction cam (7C), and the second branch (10b) of the aperture operation plate 00) is fitted into the aperture correction cam (7b). are in contact.

A C-lever (8) is pivotally mounted on the actuation ring (7) about a shaft (9). C lever (8) is connected to shaft (9) K
It is biased clockwise by the force of a spring (12) hooked onto a spring hook (8C) K formed at one end near the other end. Also, from the C lever (8) there is a lever that moves to the rear of the lens.
(3d) extends, a pin (8a) extending toward the front of the lens is implanted, and an arm (8b) further extends toward the front of the lens.

When the lens is attached to the camera body, the interlocking lever (8d) is engaged with and pushed by the lever on the camera body side, and follows when the lever on the camera body side is retracted. The pin (8a) is an aperture stop pin, and when the C lever (8) rotates clockwise around the shaft (9), the fixed lens barrel (1) and the attached lens barrel (
The preset ring (6) is fitted so as to be sandwiched between the
) is installed at a position where it comes into contact with an aperture stop cam (6a) formed on the inside of the aperture stop cam (6a).

The operation of attaching the zoom lens to the camera body and the narrowing down operation during photographing in this embodiment will be explained with reference to FIG. When the lens is separated from the camera body, the C lever (8) is rotated clockwise by the biasing force of the spring (12), and the pin (8a) comes into contact with the aperture stop cam (6a) and stops. There is. However, in Figure 2, the aperture is set fully open, so the pin (8) is already pinned (
8a) is in contact with the throttle stop cam (6a). At other aperture values, the arm (8b) pushes the first branch (1oa) and the aperture operation plate (10) rotates clockwise against the biasing force of the spring (13). and
Narrowing down is being done. Also, therefore, the second branch (10
b) and the opening correction cam (7b) are separated.

When the interchangeable lens is attached to the camera body, the interlocking lever (8d) is pushed counterclockwise by the lever on the camera body side, and the C lever (8) is pushed counterclockwise against the biasing force of the spring (12). , the second branch (10) of the diaphragm actuation plate (10)
b) rotates until it just contacts the opening correction cam (7b). At this time, the aperture is opened regardless of the set aperture value.

In Figure 2, the aperture is set fully open, so the pin (8a) and aperture stop cam (6
Due to the contact with a), the C lever (8) has already been rotated counterclockwise, and the aperture is opened.

Next, when the release operation is performed, the lever on the camera body side is retracted, the interlocking lever (8d) is unlocked, and the C lever (8) is centered around the shaft (9) by the biasing force of the spring (12). rapidly rotates clockwise.

Along with this, the first branch (
ioa) is pushed, the aperture operation plate (10) rotates clockwise, and the aperture is narrowed down. When the pin (8a) on the C lever (8) comes into contact with the aperture stop cam (6a), the C
The lever (8) stops, an aperture diameter corresponding to the set value is obtained, and then a shutter (not shown) is opened and closed to take a picture.

After the shutter is closed, the lever on the camera body side performs a return operation, and this lever engages with the interlocking lever (8d) to rotate the C lever (8) counterclockwise against the biasing force of the spring (12). make it move. Along with this rotation of the C lever (8),
The first branch part (10a) engaged with the arm part (81)) follows the arm part (8b) by the urging force of the spring (13), and the aperture operation plate 00) rotates counterclockwise. When the lever on the camera body side has returned to its original position, the aperture is opened.
The branch portions (], Ob) come into contact with the aperture correction cam (7b) K, the diaphragm operation plate (10) stops, and the diaphragm opens. During the above narrowing and opening operations, the operating ring (7) and cam plate (
7a) does not work.

Next, the zooming operation will be explained with reference to Fig. 1. First, when the zooming (2c) is rotated, the rotating lens barrel (
2) rotates. The cam groove is opened by the rotation of the rotating lens barrel (2).
(2aX2b) The K-fitted tail pin (3bX4a) is driven, and the pins (3b) and (4a) straight-travel lens barrels (31 (4) are parallel to the optical axis, respectively, following the straight groove (1aX1b) of the fixed lens barrel (1). The lens group (L) held by the linear lens barrel (3) and the lens group (not shown) held by the linear lens barrel (4) move respectively to perform zooming.

Next, referring to FIG. 2, a description will be given of the operation for correcting the open aperture diameter during zooming when the lens is attached to the camera. FIG. 2 shows a state in which the rectilinear lens barrel (3) has moved furthest to the front of the lens, and at this time it is in a long focal state. Also, in the figure, the preset ring (6) is set to open.

When zooming is performed from this state and the rectilinear lens barrel (3) moves downward in the figure, the -r zoom (3a) also moves linearly,
When the aperture correction cam (7c) is pushed by the arm (3a), the cam plate (7a) and the operating ring (7) rotate counterclockwise. At this time, the diaphragm operation plate (1o) moves straight along with the rectilinear lens barrel (3), but the second branch (10)
b) operates according to the shape of the opening correction cam (7b), and the aperture operation plate 00) rotates slightly clockwise. This rotation slightly closes the aperture blades (11) and reduces the aperture diameter.
It will be done.

On the other hand, as the actuation ring (7) rotates counterclockwise, the shaft (9) of the C lever (8) on the actuation ring (7) also rotates counterclockwise. However, the C-lever (8) is biased clockwise by the spring (12), and the interlocking lever (8d) is locked by the lever on the camera body, preventing it from moving clockwise. Actuation ring (
It cannot be rotated in the same way as 7), and the pin (8a)
moves radially outward while moving counterclockwise with the optical axis as the center. Further, the arm (8b) moves slightly to the left in the figure as the shaft (9) moves to the left when viewed from the arm (8b). This amount of movement corresponds to the amount of rotation of the aperture operation plate (101) during zooming, and the first branch (10a) and arm (8b) move by the same amount while remaining in contact.

Next, the aperture correction when the aperture is narrowed down will be explained. If we pay attention to the relative position of the pin (8a) on the C lever (8) and the aperture stop cam (6a) formed by the pre-centering ring (6), we can see that it is set to the long focal point side as shown in Figure 2. Sometimes the pin (8a) is located clockwise about the optical axis, ie, closer to the opening of the aperture stop cam (6a). On the other hand, when the focal length is set to the short focal length side, the pin (8a) is located toward the counterclockwise direction 1, that is, toward the small aperture, as shown in double rows. Therefore, when the C lever (8) rotates clockwise around the shaft (9) during shooting, the aperture stops at the long focus side even if the aperture value set by the pre-centering ring (6) is the same. Since the pin (8a) comes into contact with the cam (6a) at a position closer to the open aperture and the short focal length side, the aperture is narrowed down to different aperture diameters.

As described above, the wide-open aperture correction and the aperture diameter correction at the time of stopping down are performed, but by changing the inclination and shape of the wide-open correction cam (7b) formed on the cam plate (7a) and the aperture diaphragm (7C). , can be applied to various interchangeable lenses. Further, the linear grooves (1a) (Ib) of the fixed lens barrel (1) may be formed into a cam shape, and in this case, the shape of the cam formed on the cam plate (7a) is made to match the movement of the aperture device. Just leave it there.

In addition, in the aperture device, a holding plate (14), aperture blades (
11) The configuration of the diaphragm operation plate (10) may be changed to various configurations, such as a configuration in which the diaphragm operation plate (10) is provided with a groove and the diaphragm blade (11) is provided with a pin, for example, contrary to the embodiment.

Further, although the actuation ring (7) in the above embodiment has an annular shape and rotates around the optical axis, it may be formed into a C-shaped lever similar to the C-lever (8). In this case, for example, in FIG. 2, the shaft of the lever is located near where the cam plate (7a) is formed, and the cam plate (7a) is located near where the shaft (9) of the C lever (8) is located. ), and by forming the arm (3a) and the second branch (10b) accordingly, the same effect as in the above embodiment can be obtained.

In addition, if there is no need to perform correction when the aperture is in the open aperture state, the open aperture correction cam (7b) formed on the cam plate (7a) can be used.
When zooming, the slope of the second branch (10b
) should be set at an angle that allows it to move straight without rotating.

Furthermore, in FIG. 2, the cam plate (7a) and the arm (8b) are arranged so as to overlap, and the second branch (10b) is always in contact with both the cam plate (7) and the arm (8b). Like lv
The crotch ridge and the first branch part (10a) are no longer necessary.

Furthermore, in the embodiments, a so-called stop-down habit lens is described in which the diaphragm device as a whole is biased towards the aperture side, but conversely, it is a so-called open habit lens where the aperture device is biased towards the open aperture side. The present invention can also be applied to. In this case, the force relationship between the weak spring (13) that biases toward the open side and the strong spring (12) that biases toward the narrowing side in this embodiment is reversed so that the entire force is biased more strongly toward the open side. The lever on the main body side forcibly pushes the side corresponding to the interlocking lever (8d).

Further, although the zooming method of the embodiment is performed by rotating the zoom ring, it is also possible to perform zooming by moving the zoom ring in a straight line.

Furthermore, it is of course possible to use a lens fixed to the camera body instead of an interchangeable lens that can be attached to and removed from the camera body as in the embodiment.

Effects As stated in 2.2 above, the present invention provides an aperture device for a zoom optical system, in which an aperture operation plate that opens and closes the aperture by rotating with a drive unit is provided on a member that moves with the zoom operation, and further includes:
A diaphragm lever that performs a diaphragm operation and drives a retrieving operation plate is pivotally mounted on a rotatable operating member by an axis different from the center of rotation of the operating member, and a cam portion is formed on the operating member. The drive section is configured to engage with the drive section.

Therefore, when the actuating member is rotated by the drive unit in conjunction with the zoom operation, the rotation axis position of the aperture lever changes, the amount of operation of the aperture lever and the aperture operation plate changes, and the aperture diameter is corrected. Therefore, it is possible to obtain an aperture control device that can correct the aperture diameter with an extremely simple component configuration. Furthermore, when narrowing down, only the aperture lever and the aperture operation plate rotate, so there is no need to rotate a large member such as an operating member including a cam part, and the operation can be performed with relatively weak force. can. For this reason, it is possible to reduce shocks and the like during narrowing down.

Furthermore, since the cam portion and the like do not rotate, the space required for rotation can be reduced.

It is possible to correct the open aperture diameter.

FIG. 2 is a perspective view of a main part of the internal structure of the same embodiment.

3... Moving member, 3a... Drive unit, 7... f/[
The movement is IS material, 7C... cam part, 8... aperture lens,
81] ... Aperture interlocking table 6.10 ... Aperture operation board, 1
0a...Engagement part.

Applicant: Minolta Camera Co., Ltd. Figure 1 the law of nature No.? figure

Claims (1)

[Claims] 1. In a diaphragm device of a zoom optical system that performs diaphragm aperture correction to prevent fluctuations in aperture value due to zoom operation, a drive formed on a movable member that moves with zoom operation. a diaphragm operation plate that moves integrally with the movable member and is rotatable with respect to the fixed part of the lens barrel and has an engaging part; an actuating member that is provided to rotate with respect to the part and rotates when driven by the driving part; and an actuating member that is pivoted on the actuating member and is not the rotation center of the actuating member, and that is attached to the engaging part. An aperture control device for a zoom lens, which includes an aperture lever that has an aperture interlocking part that extends to engage with the aperture lever and that drives the engaging part to perform aperture narrowing. 2. The actuating member has a second cam part, which engages with the engaging part of the aperture operation plate or a separately provided second engaging part, and 1. The actuating member has a second cam part that engages with the engaging part of the diaphragm operation plate or a separately provided second engaging part, and 1. Aperture control device 06 for a zoom lens according to claim 1, characterized in that the position of the aperture operation plate is regulated so that the aperture diameter is set to an open aperture diameter, and the operating member is a ring that rotates around the optical axis of the lens. An aperture control device for a zoom lens according to claim 1 or 2, characterized in that the aperture control device is formed in a shape.