JP3049690B2 - Anti-vibration optics - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration optical system,
In particular, the present invention relates to an optical system having a configuration in which a part of the optical system is decentered parallel to a direction perpendicular to the optical axis. 2. Description of the Related Art In the case of image stabilization to prevent the image point from moving due to vibration applied to a camera during photographing, or a shift lens for giving a special photographing effect to a photographed image, and further, an optical reading device Optical system for auto tracking
Moving one-part elements are known. [0003] Normally, camera shake has a large effect on the image due to the long exposure time when photographing, and when images are taken from a moving car, ship, helicopter, or the like, high-frequency vibration is applied to the camera and image blur occurs. Occurs. This phenomenon is particularly remarkable in a telephoto lens. For this reason, it is considered that an optical system for image stabilization becomes indispensable for a camera at the time of hand-held shooting or shooting from a vehicle. SUMMARY OF THE INVENTION The present invention provides a highly responsive
With compensation of image displacement, an object of the this <br/> to provide an optical system equipped with parallel eccentric portion that allows for the effective movement of the image with a small eccentricity. SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an image forming method in which a part of a plurality of lenses is decentered in parallel in a direction perpendicular to an optical axis by an actuator. a vibration-proof optical system for correcting image displacement on the surface, have a positive lens on the object side of the portion of the lens, correct the image displacement
Of the image displacement to the eccentricity of some of the lenses
The value of the ratio of the positive amount is 1 or more . You
In other words, in the image stabilizing optical system of the present invention, the lateral magnification of the parallel decentered optical element (the part of the lens) is βa, and the magnification of the optical element on the image side is βb (where the optical element when when the element is not present and .beta.b = 1) to, | βb (1-βa) | has to satisfy ≧ 1 becomes conditions. FIG . 1 and FIG. 2 show an embodiment of the present invention, respectively. Figure 1 is an imaging lens system in the first embodiment, in order focal a first lens group 5, the second lens group 6, and a third lens group 7. Each lens system is composed of one or more lenses. F is an image plane. The second lens group 6 is supported by a supporting device (not shown) so that it can be freely decentered in a direction perpendicular to the optical axis of the imaging lens system, and is two-dimensionally driven by an actuator 3 such as a piezo element. Is driven. That is, in the figure, the actuator 3
Is drawn to move the second lens group 6 in the vertical direction, but another set of actuators is provided to move the second lens group 6 in the horizontal direction without causing mechanical interference with the vertical movement. Is assumed to be driven.
Also, a vibration detection sensor 4 such as an accelerometer or a gyroscope detects vertical vibrations, and another set of vibration detection sensors is provided in addition to the one shown in the figure to detect horizontal vibrations. Since the amounts are input to the respective actuators 3, the second lens group 6 moves in a direction in which the detected amount becomes zero in accordance with the two-dimensional vibration, and cancels the image plane blur. A shift in a direction parallel to the optical axis due to vibration, that is, a focus movement is not shown, but is corrected by an automatic focus detection mechanism. The correction is similarly performed in the case of the optical arrangement shown in FIG. Here, the amount of movement of the second lens group 6 in the direction perpendicular to the optical axis in FIG. 1 is d, the amount of blur correction on the image plane corresponding to d is D, and the sensitivity is L (= D / d), when the magnification of the second lens group 6 is βa and the magnification of the third lens group 7 is βb, D
= Βb (1−βa) d = Ld, and | L | = | βb
By setting βa and βb that satisfy the condition of (1−βa) | ≧ 1, a vibration-proof optical system having a sensitivity L of 1 or more can be realized. The optical system shown in FIG. 2 includes a first lens group 5 and a second lens group 6 which is a moving lens group. The sensitivity is L (= D / d), and the magnification of the moving lens group 6 is βa. D = (1−βa) d = Ld, | L | = |
By setting βa that satisfies the condition of (1−βa) | ≧ 1, a vibration-proof optical system having a sensitivity L of 1 or more can be realized. In FIGS. 1 and 2 below, the sensitivity L =
A numerical example of the power arrangement when the value is set to -1.5 is shown. (Example Corresponding to FIG. 1) First Lens Group (5) ψ = 2.0 Principal Point Spacing 0.15 Moving Lens Group (6) ψ = −2.1429 Principal Point Corner 0.3 3 lens group (7) ψ = 0.9091 (Example corresponding to FIG. 2) First lens group (5) ψ = 2.5 Principal point interval 0.12 Moving lens group (6) ψ = −2.1429 In the above examples, the stabilization of the image plane in the image forming optical system has been described. However, the present invention can be applied not only to the image forming optical system but also to an afocal optical system such as a telescope or binoculars. The correction method, the expression of the sensitivity to the arrangement of the lens groups, and the like are the same as those in the case of the imaging optical system. Conventionally, there has been a problem with the response speed of the actuator for vibrations of high frequency and large amplitude, and correction has been difficult. However, the response speed is 1 like a piezo element.
There is no problem if a very fast element of 0-5 seconds is used for the actuator , but the displacement of a general piezo element is very small, several μm to several tens μm. Therefore, if a stacked piezo element or a displacement expansion type is used, the displacement can be made several hundred μm to several mm. By using this displacement expansion type piezo element as an actuator and setting the sensitivity of the lens group for parallel eccentricity to 1 or more, it is possible to sufficiently correct even a high frequency and large amplitude vibration. Since the response speed is increased by the combination of the present invention and the piezo element, the number of times of signal feedback from the sensor to the actuator can be increased, and the vibration can be corrected in real time. Further, there is an advantage that the control system is simplified as compared with the related art. According to the present invention described above, the image displacement on the image plane can be easily corrected through the moving means for parallel eccentricity in the direction perpendicular to the optical axis.

[Brief description of the drawings] FIG. 1 is a diagram of a first embodiment of the present invention. FIG. 2 is a diagram of a second embodiment of the present invention. [Explanation of symbols] 3 Actuator 4 Vibration detection sensor 5 First lens group 6 movable second lens group 7 Third lens group

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Nozomi Kitakishi               770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa               Inside the Tamagawa Plant of Canon Inc.                (56) References JP-A-47-41853 (JP, A)                 JP-A-50-137555 (JP, A)                 Tokiko 57-7415 (JP, B2)                 Tokiko Sho 41-8558 (JP, B2)

Claims (1)

(57) [Claims] An anti-vibration optical system that corrects an image displacement on an image plane by decentering some of the lenses in parallel in a direction perpendicular to the optical axis by an actuator, and have a positive lens, when correcting the image displacement
Of the correction amount of the image displacement with respect to the eccentric amount of the partial lens
An anti-vibration optical system , wherein the value of the ratio is 1 or more .