JPH02238430A - Vibration proofing optical system - Google Patents

Abstract

PURPOSE:To miniaturize the whole device by placing a first group and a second group at a specific distance, setting a port on an optical axis separated by a specific distance to an image surface side from a principal point of the image side of a second group as a upporting point so that a second group becomes turnable and placing it in front of a photographing system, and correcting a blur of a photographing image at the time when the photographing system is inclined by turning a second group. CONSTITUTION:When focal distances of a first group 1 and a second group 2 are denoted as f1 and f2, respectively, and satisfies inequality -f1<f2 and when a principal point interval of the first group 1 and the second group 2 is denoted as (e), the first group 1 and the second group 2 are placed so as to become (e)=f1+f2. In this state, a point on an optical axis separated by about -f1 to an image surface side from a principal point of the image side of the second group 2 is set as a supporting point 3 so that the second group 2 becomes turnable and placed in front of a photographing system, and a blur of a photographing image at the time when the photographing system 11 is inclined is corrected by turning the second group. In such a way, a vibration proofing optical system 10 by which a turning relation is simplified and the supporting point 3 at the time of turning the second group 2 is brought close to the second group 2, and the whole device is miniaturized can be obtained.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an anti-vibration optical system, and particularly to an anti-vibration optical system, which is arranged in the direction of a photographing system, and which optically prevents blurring of photographed images when the photographing system vibrates (tilts). The present invention relates to an anti-vibration optical system suitable for photographic cameras, video cameras, etc., which stabilizes photographed images by performing static correction to obtain still images.

(Prior Art) When attempting to photograph a moving object such as a moving car or aircraft, vibrations are transmitted to the photographing system, causing blur in the photographed image.

2. Description of the Related Art Various types of anti-shake optical systems have been proposed that have a function of preventing blur in photographed images.

For example, in Japanese Patent Publication No. 56-211:13, according to the output signal from the detection means for detecting the vibration state of the optical device,
The image is stabilized by moving some of the optical members in a direction that offsets the vibrational displacement of the image due to vibration.

Japanese Patent Laid-Open No. 61-223819 discloses an imaging system in which a refractive variable apex angle prism is disposed closest to the subject, and an image is captured by changing the apex angle of the refractive variable apex prism in response to vibrations of the imaging system. The image is stabilized by deflecting it.

Special Publication No. 56-34847, Special Publication No. 57-7414
In the above publications, an optical member that is spatially fixed against vibration is arranged in a part of the imaging system, and by utilizing the prism effect generated in response to the vibration of this optical member, the photographed image is deflected onto the imaging plane. I am getting a still image.

In addition, it uses an acceleration sensor to detect vibrations in the shooting system,
There is also a method of obtaining a still image by vibrating a lens group in the photographing system in a direction perpendicular to the optical axis in accordance with the signal obtained at this time.

In addition, in U.S. Patent No. 2959088, an afocal system consisting of two lens groups, a first group and a second group, each having negative and positive refractive powers with the same absolute value of focal length f, is placed at the front of the photographing system. We have proposed an anti-vibration optical system using an inertial pendulum system in which the second group is used as a movable lens group for anti-vibration when the system vibrates, and is gimbally supported at its focal position.

(Problem to be solved by the invention) Generally, an anti-vibration optical system is placed in front of the photographing system, and a part of the movable lens group of the anti-vibration optical system is vibrated to eliminate blur in the photographed image and obtain a still image. If you try to do this, the entire device will become larger,
Further, there is a problem in that the relationship between the amount of correction for blurring of the photographed image and the amount of movement of the movable lens group becomes complicated, which complicates the mechanism of the entire device.

Another problem is that when the movable lens group is vibrated, the amount of decentering aberrations that occur increases, resulting in a significant drop in optical performance.

For example, in the above-mentioned US Pat. No. 2,959,088, the second group, which is a movable lens group, is gimbally supported at a position on the optical axis that is separated from its principal point by a focal length f.

In order to reduce aberration fluctuations when the second group is vibrated, the focal length of the second group must be adjusted! It is better for lf to be as large as possible. However, if the focal length sf is increased, its support point will be displaced to the rear of the photographing system, and for example, the counterweight will be located farther away from the second lens group, resulting in an increase in the size of the entire apparatus.

On the other hand, in order to reduce the size of the entire device, the focal length f of the second group can be made smaller, but this poses a problem in that eccentric aberration fluctuations increase when the second group is vibrated.

The present invention is arranged in front of the photographing system to simplify the rotational relationship of the movable lens group due to the vibration of the photographing system in order to prevent blurring of the photographed image that occurs when the photographing system vibrates, and also to make the movable lens group decentered. The object of the present invention is to provide a vibration-proofing optical system that produces less decentering aberrations when the camera is used, and that is well-corrected while reducing the size of the entire device.

(Means for Solving the Problems) The anti-vibration optical system of the present invention has a first lens having a negative refractive power in order from the object side.
An optical system having two lens groups, a lens group and a second group with positive refractive power, wherein the focal lengths of the first group and the second group are respectively fl,
The first and second groups are arranged so that when f2 satisfies the condition -fl<f2, and when e is the principal point interval between the first and second groups, e=fl+f2, The second group is arranged in front of the imaging system so that it can rotate about a point on the optical axis that is approximately (-f1) away from the image-side principal point of the second group toward the image plane as a fulcrum. The present invention is characterized in that blurring of a photographed image when the photographing system is tilted is corrected by rotating the second group.

In particular, in the present invention, the holding member that holds the second group includes:
It is characterized in that a counterweight is provided to balance the weight of the second group with respect to the Moegi fulcrum.

(Embodiment) FIG. 1 is a schematic diagram of a main part of an embodiment in which the image stabilization optical system of the present invention is mounted in front of a photographing system (fixed focal length grass lens, zoom lens, etc.).

In the figure, IO is an anti-vibration optical system, which is installed in front of the photographing system 11. The anti-vibration optical system 10 includes two lens groups, in order from the object side: a first group with negative refractive power (focal length @f1) and a rotatable second group with positive refractive power (focal length ll!f2). have.

The first group and the second group are arranged so as to satisfy the equation e=fl+f2, where e is the interval between their principal points. That is, the first group and the second group
The group forms an afocal system.

The first group 1 is held by a lens barrel (not shown) and fixed to an imaging system (camera body). The second group 2 forms an object image (virtual image) formed in the focal plane by the first group 1 at infinity.

Reference numeral 3 denotes a fulcrum on the nine axes 11a for rotating the second group, which is made of, for example, a gimbal support that supports movement in all directions, and is located at a distance (-fl) from the image-side principal point of the second group 2. It is in. 5 is a holding member that holds the second group. A counterweight 4 is provided at the other end of the holding member 5, and has a weight that balances the weight of the second group, which rotates the second group about the fulcrum 3. 6 is an imaging plane.

In this embodiment, for example, the photographing system 11 (camera body) has an angle θ
When tilted, the first group 1 and the imaging system 11 are tilted at the same angle θ. On the other hand, the second group is spatially fixed by a counterweight 4. In other words, the initial posture is maintained. At this time, the first group and the second group are configured as described above, and the second group is made to produce a ray deflection angle that is the same angle as the inclination angle of the imaging system, simplifying the rotational relationship, and The fulcrum for rotating the second group is positioned as close to the object side as possible, and the camera shake is corrected to obtain a still image while reducing the size of the entire device.

In particular, the focal length of the first and second groups is 1111 fl, and f2 is fl
<f2, that is, the first and second groups constitute an afocal system in which the angular magnification γ is γ×1. This allows the fulcrum 3 to be positioned closer to the object than the rear focal point of the second group, thereby reducing the size of the entire device when rotating the second group. In this embodiment, it is preferable to set the focal length @f2 of the second group as -1.03fl<f2<-2fl from the viewpoint of downsizing the entire device and correcting aberrations.

FIG. 2 is a schematic diagram for explaining the anti-vibration effect of the anti-vibration optical system 10 at this time, and in this figure, the anti-vibration optical system is shown as a thin lens.

Let A be the intersection of the first group and the optical axis 11a when the imaging system is not tilted, and B be the intersection of the second group 2 and the optical axis 11a.

When the imaging system is tilted upward by a small angle θ1 due to vibration, etc.,
The first group 1 is similarly tilted by an angle θ1, but the second group 2 maintains its initial attitude.

In Fig. 2, for simplicity, the photographing system and the first group 1 are relatively fixed, and the subject moves downward at an angle of 101 degrees.
Point B also shows a state where it has moved to point B1, which is tilted downward by 101 degrees about fulcrum 3. (However, B, B1=-fl・θ
It is 1. ) Here, consider the imaging state of point C at the center of the screen. The object in the first non-vibrating state is 9-axis 11
It is at point D on a. Tracing the ray backwards from point C, we get the second
The light beams incident on the group are parallel. Since the light beam passing through point B1 is not subjected to refraction, it travels parallel to the optical axis.

The rear focus of the first group 1 and the front focus of the second group 2 are configured so that the first and second groups satisfy the formula e=fl+f2, so when there is no tilt, the They match at point D. On the other hand, the luminous flux when tilted is from point D to B-B
The image is formed at a point D1 located downwardly from the 9th axis by the same distance as l.

That is, in FIG. 2, D-DI=-fl·θ1.

Consider the imaging state of the image point D1 by the first group 1 at this time. Imaging light at a point D1 located at a distance of f1·θ1 from the optical axis 11a on the image-side focal plane of the first group is emitted in parallel from the first group, and the inclination θ at that time is determined by the imaging relational expression, D-DI= fl・θ
Therefore, θ=-01.

That is, the light is emitted parallel to the same direction as the object in the initial state. Conversely, this means that the subject does not move from point C at the center of the screen even if the photographing system is tilted.

The above description has been made using a thin lens system as an example, but the same applies to a thick lens system as long as the distance between the principal points is small.

In the explanation of Fig. 2, we took the center of the screen as an example to show the case where the photographing system vibrates and is tilted, but the first and second groups constitute an afocal system as described above, even at points other than the center of the photographic screen. It is clear from this that a still image can be obtained with the blurring of the photographed image corrected in the same way as in the center of the screen.

FIG. 3 is a lens sectional view of a numerical example in which the image stabilizing optical system 1o of the present invention is mounted in front of a zoom lens as the photographing system 11.

In the figure, 10 is an anti-vibration optical system, and the first group 1 has a negative refractive force.
and a rotatable second group of positive refracting forces. 11 is a photographing system, which includes a focus lens group F and a variable magnification lens group V.
, a correction lens group C for correcting image fluctuations due to zooming, and an imaging lens group R. Sho ST
is the aperture. Next, a numerical example according to FIG. 3 will be shown.

In the numerical examples, Ri is the radius of curvature of the i-th lens surface from the object side, Di is the thickness and air distance of the i-th lens from the object side, and Ni and νi are the i-th lens surface from the object side, respectively. These are the refractive index and Ahe number of the lens.

The aspherical shape has an X-axis in the nine-axis direction, an H-axis in the direction perpendicular to the optical axis,
The traveling direction of the light is positive, R is the paraxial radius of curvature, A, B, C,
When D and E are each aspherical coefficients, it is expressed by the formula +DH8+EHlO.

Numerical actual/Ih example (anti-vibration optical system) [1 mouth = aspherical surface D N 49+71 11 ~ -90. Jl゛ sphere coefficient f2 - 94 e==4 1st n- 63.272 B~ 6.521 x 10-' C 5.806 xlO-" D- -1.878 X IQ-13 5th side R-
54.477 8・-6.56! C- -4.347 D~ 2.773 XIO
2- 45.63 D 2・FNo-I:1.
4 to 1.7 N I-1.80518 N 2-1.60:il+ 1-57.4 1-25.4 2-60.7 R 3-163.62 R 4- 40.88 R 5- 121 .42 R 6-16:I. 97 R 7- 14.67 R 8--18. +4 n 9- 17.54 1110- -93.94 nl1- -24.06 RI2--1:14.02 Rl3- 105.88 1114- -27.07 RI5- Aperture nl6- 38.07 1117-156. 99 Rl8- -24.96 RI9- -74.34 rl20- 22.98 R21・944 98 n22- 23.30 R23- 11.75 1124- 1171.81 D 3- 0. +5 D 4- 5.00 D5・Variable D6~1.20 0 7= 4.54 D 8- 1.00 D9・350 DIO-Variable DI+・1.00 DI2=Variable DI3- 3.90 014- 1. 30 DI5- 2.00 016- 3.20 017- 1.85 018- 1.20 019- 0. +5 D20- 4.00 D21・10.98 D22- 1.00 023- 1.88 D24- 2.50 N 3-1.62299 υ 3-58N 4-
1.83400 ν 4-37.2N 5-1.7
+299 ν 5=53.1lN 6=1.846
6 [i ν 6-2: 1.9N 7 seals 1.69680
ν 7-55.5N 8%1.71299 ν
B-53. 8N 9~1.62299 ν 9-5
8NI0・1.84666 ν10−23.9Ni+
・1.62299 νI1-58.1NI2-1 .
1105 1ll ν12-25.4NI3-1 .
516:13ν! :l-64.11125m R27- 1 {28 29- 46.29 15.91 D25-D27-[128- 0.15 3,60 5.00 6.00 Nl4-1.62299 ν14-58.1Nl5 −
1.5 16:l:I ν15-64.1 In this example, the fulcrum position for rotating the second group does not have to be exactly (-f1) away from the ten points on the image side of the second group. , it may be set within a permissible range of ±10%, for example, as long as an acceptable still image can be obtained due to vibration.

Further, in this embodiment, an auxiliary mechanism for holding the second group at the fulcrum or a damping mechanism may be provided to prevent adverse effects caused by contact of the end points.

In the present invention, based on the same idea as described above, the first group is placed at a point a distance f1 away from the first group, in place of the second group, that is, the first
It can be supported and rotated at the front of the group to provide a vibration-proofing effect.

(Effects of the Invention) According to the present invention, the first group and the second group of optical properties as described above are
By placing the optical system with the group in front of the photographing system, the rotation relationship can be simplified, the fulcrum when rotating the second group can be moved closer to the second group, and the entire device can be made more compact. A vibratory optical system can be achieved.

Further, by providing a counterweight for the second group, it is possible to correct blur in a photographed image without using a vibration detection means such as an acceleration sensor, and to achieve a vibration-proof optical system that can easily obtain a still image.

Further, according to the present invention, if the length from the photographing system to the image is fixed, for example, there will be restrictions on the positions of the support point 3 and the counterbalance weight, or in that case, US Pat.
In the conventional example shown in No. 59088, there is a restriction that a support point is placed at the focal position of the second group 2, and a large restriction condition is placed on the focal length f2 of the second group 2. However, in the present invention, the first
Since the focal length f1 of group 1 can be freely selected, the second
It is easy to increase the focal length @f2 of the group, which is advantageous for correcting aberrations. On the other hand, when the focal length f2 is the same, by moving the support point 3 closer to the object side, the entire device can be made more compact, and the counterbalance weight can also be made lighter, so the effect on size and weight reduction is tremendous.

Further, in the present invention, since f1≠−f2 is sufficient, there is no need to set el=0, and there is no restriction on the principal point positions of the first group 1 and the second group 2, which is very advantageous in terms of aberration correction. are doing.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the essential parts of an embodiment of the anti-vibration optical system of the present invention installed in front of the imaging system, and Fig. 2 is a schematic diagram for explaining the anti-vibration effect of the anti-vibration optical system of the present invention. A schematic diagram, FIG. 3 is a sectional view of a lens according to a numerical example of the present invention, and FIG. 4. Figure 5. FIG. 6 is an aberration diagram in the reference state, when the imaging system is tilted by 1°, and when the imaging system is tilted by −1° in numerical examples of the present invention. In the aberration diagrams, (A) is the wide-angle end, (B) is the telephoto end, h is the incident height when the center of the luminous flux is set to 0, and y is the image height. In the figure, IO is the anti-shake optical system, 11 is the imaging system, 1 is the first group,
2 is a second group, 3 is a fulcrum, 4 is a counterweight, 5 is a holding member, and 6 is an imaging plane. wa 4 Figure (A) Mezu Doiwa 6 (A) 9F, MataenzFh 拉 difference ('/.)

Claims (2)

[Claims] (1) An optical system having two lens groups, a first group with a negative refractive power and a second group with a positive refractive power, in order from the object side, and the focal length of the first group and the second group is The first group and the second group are arranged so that when f1 and f2 respectively, the condition -f1<f2 is satisfied, and when the distance between the principal points of the first group and the second group is e, e=f1+f2. in front of the photographing system so that the second group can rotate about a point on the optical axis that is approximately (-f1) away from the image-side principal point of the second group toward the image plane side as a fulcrum. 1. An anti-vibration optical system, characterized in that the second group is arranged to correct blurring of a photographed image when the photographing system is tilted, by rotating the second group. (2) The holding member that holds the second group is provided with a counterweight that balances the weight of the second group with respect to the fulcrum. Vibrational optical system.