JPH09281545A - Zooming device and optical instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve the brightness and darkness ratio of a light quantity in the central and peripheral parts of a picture by incorporating a diaphragm device capable of performing diaphragming up to a small aperture and a subdiaphragm for setting the diameter of an open aperture at each focal distance, linked with a zooming operation and driving the diaphragm device with the zooming operation, even in an opened state. SOLUTION: A first moving frame 3 for first lenses G1 and G2 and a second moving frame 4 for second and fourth lens groups G3, G4, G7 and G8 are slidably inserted in an optical axial direction, into the inside diameter part of a cam barrel 2 rotatably inserted into the inside diameter part of a guiding barrel 1 respectively and a third moving frames 5 for third lens groups G5 and G6 is slidably inserted in the axial direction, into the inside diameter part of the second moving frame 4 as well. Further, a motor-driven diaphragm device 24 capable of performing diaphragming up to the small aperture is attached to the third moving frame 5 and the subdiaphragm 26 for setting the diameter of the open aperture at each focal distance, linked with the zooming operation is attached to the rear. Even in the opened state, the diaphragm devices is driven by the zooming operation. Thus, the quantity of light made incident on the central part of the picture can be limited.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a diaphragm aperture (FN
A zoom device including a main aperture that can change O) and a sub aperture that is located behind this main aperture and whose aperture diameter changes in conjunction with zoom operation, and particularly relates to a wide-angle zoom device and optical equipment. Is.

[0002]

2. Description of the Related Art Conventionally, an electric aperture device having an aperture diameter correction mechanism for correcting the aperture diameter in conjunction with zoom operation has been developed by the applicant of the present invention and has already been put into practical use. An electric aperture device having this aperture diameter correction mechanism is disclosed in Japanese Patent Laid-Open No. 3-15.
As described in Japanese Patent No. 834, the open FNO is determined by the open diameter (fixed open diameter in the aperture device) at the tele end, and the open aperture aperture is set by the aperture blade itself from the tele end to the wide end. Formed and open FNO by the aperture size
To determine. That is, one electric diaphragm device (main diaphragm)
In order to change the FNO, it is possible to narrow down to a small aperture and to have an aperture diameter correction mechanism that changes the aperture diameter in conjunction with zoom operation.

Further, there is a zoom device equipped with two diaphragm devices, an electric diaphragm device (main diaphragm) capable of narrowing down to a small diaphragm in order to change the FNO, and a secondary diaphragm device whose diaphragm aperture changes in conjunction with zoom operation. Are known.

[0004]

However, in the zoom device equipped with the above-mentioned one electric diaphragm device, since it also serves as a diaphragm aperture correction capable of narrowing down to a small diaphragm, the diaphragm device becomes large and there is a space disadvantage. However, there is a problem that a compact lens barrel cannot be achieved.

On the other hand, in a zoom device having two diaphragm devices, a main diaphragm capable of narrowing down to a small diaphragm and a sub diaphragm whose aperture diameter changes in association with zoom operation, the main diaphragm and the sub diaphragm are separated from each other. Therefore, compared to the above-mentioned one motorized aperture device that also functions as a diaphragm aperture correction that can narrow down to the small aperture, more light enters the middle part of the screen and the contrast ratio with the peripheral part (diagonal) of the screen However, there was a problem that the peripheral light amount became insufficient.

The present invention has been made to solve the above problems, and limits the amount of incident light in the middle of the screen,
It is an object of the present invention to provide a zoom device and an optical device that alleviate the light intensity contrast ratio of the screen middle part and the screen peripheral part.

[0007]

A zoom device according to a first aspect of the present invention is provided with a diaphragm device capable of narrowing down to a small diaphragm and a sub diaphragm that determines an open FNO at each focal length in association with a zoom operation. However, the diaphragm device is driven even in the open state by the zoom operation.

A zoom device according to a second aspect of the present invention is
The diaphragm device is driven to the vicinity of the FNO light flux at each focal length.

A zoom device according to a third aspect of the invention is
The zoom encoder detects the focal length.

A zoom device according to a fourth aspect of the invention is
A stepping motor is used as a drive source of the diaphragm device.

A zoom device according to a fifth aspect of the invention is
The sub-aperture determines the open FNO other than the TELE end in conjunction with the zoom operation and cuts the optical flare.

A zoom device according to a sixth aspect of the invention is
The sub diaphragm is located behind the diaphragm device.

A zoom device according to a seventh aspect of the invention is
In the open state, the aperture device is narrowed down to the vicinity of the FNO optical in conjunction with the zoom operation to limit the incident amount at the intermediate portion of the screen.

An optical apparatus according to an eighth aspect of the present invention includes the zoom device according to any one of the first to seventh aspects.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below.

Embodiment 1 1 is a vertical cross-sectional view of a zoom device in a wide state according to Embodiment 1 of the present invention. In the drawing, 1 is a guide cylinder, 2 is a cam cylinder rotatably fitted in an inner diameter portion of the guide cylinder 1. The first moving frame 3 and the second moving frame 4 for the first lenses G1 and G2.
Second moving frame 4 for lens groups G3 / G4, G7 / G8
Is slidably inserted in the optical axis direction. And
A cam follower 3a planted with screws or the like in the first moving frame 3 and a cam follower 4a planted with screws or the like in the second moving frame 4.
, Respectively, are fitted into the straight-moving guide grooves 1a and 1b provided in the guide cylinder 1, respectively, and further fitted into the cam grooves 2a and 2b provided in the cam cylinder 2, respectively.

A third moving frame 5 for the third lens groups G5 and G6 is slidably fitted in the inner diameter portion of the second moving frame 4 in the optical axis direction. The cam follower 5a planted in the same manner is fitted in the straight guide groove 4b provided in the second moving frame 4 and also fitted in the cam groove 2c provided in the cam barrel 2.

A holding frame 6 for holding a part of the lenses G2 of the first lens groups G1 and G2 is provided in the inner diameter portion of the first moving frame 3.
The cam follower 6a planted with screws or the like is fitted into the cam groove 3b of the first moving frame 3. Then, a focus key 8 for directly transmitting the rotation of a known ultrasonic motor 7 as a stepping motor.
, But is fitted in the focus adjustment block 9 attached to the holding frame 6 with screws or the like.

A pressing ring 10 for holding a part of the lens G1 of the first lens groups G1 and G2 is screwed to the tip of the first moving frame 3. A hood mounting ring 11 connected to the guide cylinder 1 with a screw 23 is provided on the outer periphery of the pressing ring 10.
There is a manual ring 1 on the outer periphery of the guide cylinder 1.
2 is rotatably fitted, and a manual rubber 13 is wound around the outer peripheral surface thereof.

The cam barrel 2 is connected to the zoom ring 16 by a zoom key 14 and a zoom roller 15 which are fixed to the cam barrel 2 with screws. Around the outer peripheral portion of the zoom ring 16, a zoom rubber 17 that also serves as a retainer for the zoom play removing piece 18 is wound. Further, a zoom brush 19 for a zoom encoder is fixed to the zoom key 14.

A mount 20 is provided at the rear of the guide tube 1.
The fixed cylinder 21 that is coupled to the mounting board 22 is screw-coupled, and the mounting substrate 22 is disposed between the mounting cylinder 22 and the mount 20. The mount 20 is engaged with a mount (not shown) on the camera body side 30 as an optical device.

The zoom ring 16 is rotatably fitted in a fixed barrel 21, and the zoom key 1 is moved by the zoom roller 15.
4 is thrust-controlled against the manual ring 1
The reference numeral 2 is rotatably fitted in the guide cylinder 1 and is thrust-controlled by the end 7b of the communication ring 7a of the ultrasonic motor 7 and the end 21a of the fixed cylinder 21.

An electric diaphragm device (main diaphragm) 24 capable of narrowing down to a small diaphragm is attached to the third moving frame 5 with a screw 25, and a sub diaphragm 26 for determining the open FNO is attached to the rear side. The sub diaphragm 26 has a holding plate 26a.
The shaft 26d is integrally formed with the holding plate 26a.
Is pivotally supported in the hole 5b of the third moving frame 5, thereby restricting the rotation of the holding plate 26a, and is attached to the third moving frame 5 by a patching claw (not shown) of the holding plate 26a. The Hachinos 26b is rotatably bayonet-coupled to the holding plate 26a, and by the Hachinos 26b rotating,
The diaphragm blade 26c opens and closes to determine the open FNO.

The second moving frame 4 has a second lens group G3.G.
4 and the rotation cam groove 4c of the Hachinos 26b corresponding to the differential cam between the third lens group G5 and G6, the cam follower 26e and the Hachinos 26b are connected, and the diaphragm blades 26c in each zoom range (each focal length) The opening / closing amount of is determined.

Next, the operation will be described. The holding frame 6 is rotated via the focus key 8 and the focus adjustment block 9 by the rotation of the well-known ultrasonic motor 7 or the manual ring 12, and the optical axis is set along the cam groove 3b of the first moving frame 3. Focusing is also done by moving forward and backward in the direction.

On the other hand, when the zoom ring 16 is rotated, the cam barrel 2 is moved through the zoom roller 15 and the zoom key 14.
Rotates and is guided by the cam groove 2a of the cam cylinder 2 and the straight guide groove 1a of the guide cylinder 1 to move the first moving frame 3 and the holding frame 6
However, similarly, the third moving frame 5 moves along the optical axis direction while being guided by the cam groove 2c and the rectilinear guide groove 4b to perform zooming.

At this time, the sub diaphragm 26 is provided with the second lens group G3.
With the movement of G4 and the third lens groups G5 and G6 in the optical axis direction, the Hachinosu 26b is moved by the cam groove 4c of the second moving frame 4.
Rotates, and the diaphragm blade 26c opens and closes.

FIG. 2 is an enlarged view of the main part of the electric diaphragm device (main diaphragm) 24 in the same wide state as in FIG. 1. In the figure, the alternate long and two short dashes line 27 shows the wide open FNO luminous flux and the solid line 28. Indicates the underline of the light flux at an image height of 10 mm.

In the wide open state of the first and FIG. 2,
If the electric diaphragm device (main diaphragm) 24 is narrowed to the vicinity of the FNO light flux at point 29 in FIG. 2, the light flux near the underline of the image height of 10 mm (between points 29 and 30) can be cut, and the image height illuminance ratio ( The amount of ambient light) drops off gently.

As the drive amount of the electric aperture device (main aperture) 24, the aperture amount (drive amount) up to the open FNO light flux at each focal length is stored in advance in the microcomputer, and the zoom encoder 19 (cam barrel 2) is stored. The motorized diaphragm device (main diaphragm) 24 is driven by detecting the zoom position by detecting the rotation amount of the.

FIG. 3 shows the image plane illuminance ratio in the wide open state. The vertical axis represents the illuminance ratio, and the horizontal axis represents the image height. The broken line shows the state where the electric diaphragm device (main diaphragm) 24 is not closed, and the solid line shows the open FNO.
It is in a state in which it is narrowed down to near the light flux. As is clear from this figure, the contrast ratio between the middle part of the screen and the peripheral part is alleviated, and the photograph does not appear to have insufficient peripheral light quantity.

[0032]

As described above, according to the present invention, even in the open state, the focal length is detected by the zoom encoder, and the electric aperture device (main aperture) is driven to the vicinity of the open FNO light flux at that focal length. Since it is configured such that the amount of incident light in the middle portion of the screen can be limited, there is an effect that it is possible to prevent the peripheral light amount from being insufficient or vignetting to be taken.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a zoom device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the electric diaphragm device portion of FIG.

FIG. 3 is a diagram showing an image plane illuminance ratio.

[Explanation of symbols]

 7 Ultrasonic Motor (Stepping Motor) 19 Zoom Encoder 24 Electric Aperture Device (Main Aperture) 26 Sub Aperture 27 FNO Luminous Flux

Claims (8)

[Claims] 1. A diaphragm device capable of narrowing down to a small diaphragm,
A zoom device equipped with a sub-iris that determines an open FNO at each focal length in conjunction with a zoom operation, wherein the diaphragm device is driven even in the open state by the zoom operation. 2. The FNO at each focal length
The zoom device according to claim 1, wherein the zoom device is driven to near the light flux. 3. The zoom device according to claim 1, wherein the focal length is detected by a zoom encoder. 4. The zoom device according to claim 1, wherein the diaphragm device uses a stepping motor as a drive source. 5. The sub-iris operates in conjunction with a zoom operation to obtain a T
The zoom apparatus according to claim 1, wherein the open FNO other than the ELE end is determined. 6. The zoom device according to claim 1, wherein the sub diaphragm is located rearward of the diaphragm device. 7. The zoom device according to claim 1, wherein, in the open state, the aperture device is narrowed down to a vicinity of an FNO light flux in association with a zoom operation. 8. Any one of claim 1 to claim 7.
An optical apparatus comprising the zoom device according to the item.