JPH0282113A - Camera shake vibration detecting device for camera using optical fiber gyro - Google Patents

Abstract

PURPOSE:To prevent image blurring due to a camera shake of the camera by providing optical fiber loops to the lens barrel or camera body of the camera. CONSTITUTION:The optical fiber loops 11a and 11b are provided in a surface curved in conformity with the curvature of the lens barrel 12 and a longitudinal and a lateral shake of the camera are detected through the loops 11a and 11b. Namely, the loops 11a and 11b have their winding center lines 13a and 13b at right angles to a longitudinal and a lateral shake vibration plane. Then light beam propagated in the loops 11a and 11b are inputted to detectors 45a and 45b respectively to detect variation in the intensity of interference light, and the variation is integrated and amplified by an analog integrator and outputted to driving parts 47a and 47b of a correction optical systems 46. Thus, the image blurring due to a camera shake of the camera can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vibration detection device for equipment that receives vibrations at a relatively low frequency, and is typically mounted on a camera, for example. This invention relates to a camera shake vibration detection device using an optical fiber, which is used in a system that prevents image blur by detecting low-frequency vibrations (angular velocity).

(Background of the Invention) An example in which the present invention is applied as an image blur prevention system for a camera will be described below.

Modern cameras include the detection of exposure information and focus information that determine important camera operations for photography, such as exposure determination and focus adjustment, as well as the operation control of the photographic mechanism based on this detection information, such as the detection of exposure and focus information. Many devices have been provided that automate the control of an aperture mechanism based on exposure information or the control of a lens focusing mechanism based on focus information.

However, research and development on camera shake caused by camera shake (so-called image blur) has lagged behind due to the difficulty of automating it compared to the other mechanisms mentioned above. For the most part, it was left unattended, depending on the technique.For this reason, there are often cases of failures in shooting due to so-called camera shake.

Considering the problem of automatic control to prevent image blur during shooting, firstly, image blur is caused by camera shake of the photographer who is supporting the camera, so the vibration that is the subject of control is usually It is related to low-frequency vibrations of about 1 to 12 Hz, and based on the premise that it is difficult to artificially suppress this vibration during shooting, it is possible to take pictures without image blur even if such a shooting occurs at the time of release. Second, it is necessary to detect the vibrations occurring in the camera at that time, and adjust the lens of the photographing system to eliminate the effects of this vibration. A possible solution is to perform corrective vibration in the opposite direction.

Therefore, in order to mechanically deal with this problem, one is required to have a powerful detection device that accurately detects the vibrations actually occurring in the camera, and the other is to use a camera lens system. It is necessary to have a structure capable of corrective vibration, and to provide a drive device to perform corrective vibration.

(Prior Art) In principle, the device configuration for detecting camera shake (vibration) information, which is essential when configuring the camera image blur prevention system as described above, is based on information such as angular velocity, angular acceleration, etc. It requires a vibration sensor that detects the vibration, and an integration device that electrically or mechanically integrates the signal from this sensor and outputs it as an angular displacement signal. Among these, one of the devices that can be used as the former vibration sensor is A fiber optic gyro could be considered.

The principle of this optical fiber gyro will be explained with reference to FIG. 7. Light emitted from a light source 51 is split into two by a half mirror 52, and each of the split lights enters optical fibers at both ends of an optical fiber loop 53. These incident lights propagate counterclockwise and clockwise within the optical fiber loop 53, and then exit from opposite ends, are combined by the half mirror 52, and guided to the photodetector 54. When the optical fiber loop 53 is rotating at this time, a so-called Sagnac phase difference Δθ proportional to the rotational angular velocity and expressed by the following equation (1) occurs between the light propagating clockwise and counterclockwise.

: Phase difference due to Sagnac effect : radius of optical fiber loop : Optical fiber length :Speed of light in vacuum ・Light wavelength (wavelength in optical fiber) Ω: rotational angular velocity Further, the output of interference light is expressed by the following equation (2).

I=A(1+cosΔθ) (2) (where A: constant) Therefore, by detecting the intensity change of this interference light with the photodetector 54, it becomes possible to detect the rotational angular velocity Ω.

This fiber-optic gyro is capable of configuring the entire light propagation path from the output end of the light source to the detection end of the interference light using optical fibers, and is expected to offer higher precision, longer life, and lower cost. This is one of the technologies that is currently attracting attention.

Next, problems when this optical fiber gyro is mounted on a camera as a vibration detection device will be explained based on FIGS. 6 to 8.

The example shown in FIG. 6 is for detecting vibrations in the vertical direction 41a and the horizontal direction 41b on the distal end side of the camera with respect to the photographing optical axis 41 of the camera. In this figure, 4
Reference numeral 2 denotes a lens barrel, and 46 constitutes a part of the photographing optical system, and is provided with a correction device capable of eight movements in two orthogonal axes directions perpendicular to the photographing optical axis in order to compensate for vibrations. Optical systems 47a and 47b indicate drive units for moving and driving the correction optical system 46 in the two orthogonal axes directions. The correction optical system 46 is
The image plane 48 due to camera vibration is corrected by vibrating the image plane 48.
It is possible to ensure image stabilization with image blur corrected.

In order to cause the correction optical system 46 to undergo correction vibration by the driving units 47a and 47b, FIG. 6 shows an example in which vibration detection is performed using an optical fiber gyro having the following configuration. In other words, the configuration of this vibration detection device is such that an optical fiber loop 43a in a substantially vertical position for detecting vibration in the vertical direction 41a is mounted on the side of the lens barrel 42, and an optical fiber loop 43b in a substantially horizontal position is mounted on the side of the lens barrel 42.
are provided at the top of the lens barrel 42, and the phase difference based on the Sagnac effect within these loops is detected by a photodetector (not shown), and the rotation in the directions 44a and 44b shown in the figure (that is, rotation around the vertical axis and around the horizontal axis) is detected by a photodetector (not shown). direction), and further converts this information into detectors 45a, 4 including analog integrators,
5b converts it into an angular displacement signal and sends it to the correction optical system 4.
6 drive units 47a and 47b.

(Problem to be Solved by the Invention) When we look at the phase difference Δθ due to the Sagnac effect detected by the optical fiber gyro as described above in relation to the above equation (1), we find that its sensitivity is proportional to the length of the optical fiber gyro. In order to improve measurement accuracy, it is preferable to increase the length of this optical fiber gyro.

By the way, in order to fit the optical fiber loop into the camera lens barrel in the format shown in Figure 6 above,
There are restrictions on increasing the outer diameter 63 of the loop.

In other words, since the lens barrel 4z has a curvature determined by its diameter, even if the optical fiber loop is to be housed between the inner wall 61 and the outer wall 62 of the lens barrel, it is necessary to place a large diameter planar loop in this range as shown in FIG. This is because it cannot be contained. On the other hand, if the number of turns of the optical fiber loop is increased to make the inner diameter smaller in order to increase the length of the optical fiber loop without changing the outer diameter of the optical fiber loop, the curvature of the optical fiber loop on the inner diameter side becomes extremely large, causing the optical fiber to break. This may cause problems such as distortion or distortion. Therefore, the sixth
In the configuration shown in the figure, there is a limit to the length of the optical fiber loop, and as a result, it is difficult to improve the measurement accuracy of angular velocity detection.

(Means for Solving the Problems) The present invention improves the configuration of a camera shake vibration detection device using an optical fiber gyro including the above-described optical fiber loop as a component, and improves the configuration of a camera shake vibration detection device that uses an optical fiber gyro that includes an optical fiber loop as a component. The purpose of the assembly is to provide a vibration detection device with a novel configuration that can detect vibration information with excellent measurement accuracy even when the structure of the part is limited in volume or shape.

Therefore, the camera shake vibration detection device using the optical fiber gyro according to the present invention, which has been made to achieve the above object, is characterized by detecting vertical shake vibration around the horizontal axis and/or lateral shake around the vertical axis of the camera. In a camera equipped with an optical fiber gyro that detects vibration angular velocity by detecting the Sagnac phase difference of light in two directions propagating in opposite directions in an optical fiber loop to detect vibration, the optical fiber loop is used as a detection target. The center of the shape of the loop is an axis perpendicular to the vibration vibration plane, and the loop is arranged in a curved surface curved with respect to the vibration vibration plane, or is arranged in an oval or elliptical shape. It's everywhere.

The camera shake vibration detection device of the present invention is particularly suitably applied to a camera shake prevention system in which the structure of the mounted part is restricted, and in this case, when the camera is held in a normal shooting posture. In this case, it is preferable to detect vibrations about each axis in the vertical direction and the horizontal direction within a plane perpendicular to the photographing optical axis, and to configure each axis independently.

The optical fiber gyro used in the present invention includes an optical fiber loop as a component, and this optical fiber loop may be mounted on either the lens barrel of the camera or the camera body. The so-called camera shake vibration in a camera is generally in the vertical and horizontal directions as mentioned above in a normal shooting posture, so the optical fiber loop has an axis perpendicular to the vibration plane of the shake to be detected as the winding center line of the loop. In order to have a long fiber length, the fiber is wound around a cylindrical lens barrel as a circular, elliptical or oval loop, and mounted in a curved plane along the curvature of the lens barrel. It is better to let

Further, when mounted on a camera body, it may be an oval or elliptical shape that coincides with the plane of vibration vibration.

Furthermore, the camera shake vibration detecting device of the present invention has an axis substantially parallel to the direction of the shake vibration to be detected, which is the center of the figure.
An optical fiber loop may be provided in the shape of a square, and the optical fiber loop may be arranged in a curved plane so as to have a long loop parallel to the blur vibration plane. In short, this purpose can be achieved by arranging the optical fiber in a direction along the vibration direction and causing the Sagnac effect to occur in the light traveling in the optical fiber loop due to acceleration in this direction.

(Function) According to the present invention, an optical fiber gyro can be used to easily and conveniently mount a target vibration detection device on a structurally restricted object such as a lens barrel. Moreover, since the length of the optical fiber can be increased, it is effective in improving measurement accuracy.

(Example) The present invention will be described below based on an example shown in the drawings, which is an example of the case where the present invention is applied as a system for detecting vibration for preventing image blur in a camera.

Embodiment 1 Figure 1 shows an example of a general configuration of a vibration detection device using an optical fiber gyro according to the present invention. Similarly, llb indicates a circular optical fiber loop provided for detecting lateral camera shake (shake around the vertical axis in the drawing).

These optical fiber loops lla and llb are arranged so as to be located within a curved plane along the curvature of the lens barrel 12.

According to such a configuration, the vibration vibration shown in the d direction in the figure is detected for the optical fiber loops lla and llb shown in the drawing, and the sensitivity is improved due to the longer fiber length compared to the example in FIG. 6. Highly accurate vibration detection becomes possible.

In the format of this example, the optical fiber loop lla provided for detecting longitudinal vibration, for example, has its winding center line 13
There is no particular restriction on the range of winding around the lens barrel 12, as long as a is substantially perpendicular to the longitudinal vibration vibration plane and satisfies the condition that it is the center of symmetry of the loop.

The light propagated through the optical fiber loop lla is input to a detector 45a including, for example, a photodetector and an analog integrator, and a known photodetector such as an St photodiode (not shown) is used to detect changes in the intensity of the interference light. This is detected, integrated and amplified by an analog integrator (not shown), and outputted to the drive section 47a of the correction optical system 46. The drive section can be constructed using, for example, the device described in Japanese Patent Application Laid-Open No. 62-47011.

Example 2 The optical fiber gyro mounted on the camera of this example shown in FIG. 2(a) has optical fiber loops 21a and 21.
b is oval, and is assembled to the lens barrel 12 with its oval axis aligned with the generatrix direction of the lens barrel.
This is similar to Example 1. Therefore, this figure 2 (
In a), the loop has almost no curvature.

The example shown in FIG. 2(b) is an example of the embodiment except that the oval optical fiber loops 22a and 22b are assembled to the lens barrel 12 with their oval axes aligned with the circumferential direction of the lens barrel. This is similar to 1. This example has the advantage that it requires less space for loop assembly than the example shown in Figure 2 (a), and can be assembled without restrictions even when the lens barrel is not long, such as a telephoto lens. be.

In these examples, the principle of imaging and detection and the configuration of the device are the same except that the shape and direction of the loop are different.

Example 3 The optical fiber gyro mounted on the camera of this example shown in FIG. 3 has oval optical fiber loops 21a, 21.
This figure shows an example in which the camera body 25 is mounted in a flat state on the camera body 25.

Such an oval shaped optical fiber loop/21a, 2
1b, the loop can be arranged in a plane parallel to the vibration surface to be detected in the camera body 25, and since the lens barrel 12 is not equipped with an optical fiber gyro, it is not suitable for a camera that combines a large number of interchangeable lenses. This has the advantage that the entire camera equipment including interchangeable lenses can be provided at low cost.

Embodiment 4 FIGS. 4 and 5 show other embodiments of the present invention, and in order to avoid complication of the figures, only the means for detecting the horizontal shake vibration of the camera are shown. The illustration of a means for detecting longitudinal vibration is omitted.

In the example shown in FIG.
The lens barrel 72 is approximately shaped like a figure 8 (sash shape) over b.
An example is shown in which an optical fiber loop 71 is wound around the entire circumference. The other configurations and effects except for the method of winding the optical fiber loop 71 are the same as those of the above embodiment, and therefore the explanation thereof will be omitted.

In this example, a portion 71b located above and a portion 71a located below the lens barrel 72 of the optical fiber loop 71 form a figure 8, so when viewed from the sensitivity axis 75, the portion 71b located above and the portion 71a located below The winding direction is the same, and as a result, the direction of propagation of light within the two closed inner parts of the figure 8 is equal, and the Sagnac effect due to the addition of angular velocity is accelerated, e.g. Compared to Example 1, this has the advantage of increasing the sensitivity and increasing the output power, which is similar to when the optical fiber loop is made longer. Moreover, the work of winding the optical fiber loop is extremely simple and easy, as it can be done by providing a pin on the lens barrel and hooking the fiber onto the pin.

Another advantage is that the thin space between internal walls can be used efficiently. Note that in the optical fiber loop 71 provided in the figure 8 shape of this example, point 73 is the center of the figure.

The example in FIG. 5 shows an example in which the figure-8 shaped optical fiber loop 81 in the example in FIG. 4 is incorporated into the camera body 48, and the optical fiber loop 81 is incorporated from the bottom of the camera to between the pentaprism. .

As mentioned above, these examples are for detecting horizontal shake vibration of the camera, but it goes without saying that in order to detect vertical shake vibration, it is sufficient to tilt the loop 90" when viewed from the photographing optical axis. stomach.

(Effects of the Invention) As explained above, the camera shake vibration detection device using the optical fiber gyro according to the present invention has a structure in which an optical fiber loop is arranged in the lens barrel or camera body of the camera. The present invention provides a high-precision vibration detection device that is easy to manufacture and has a space-saving structure, and has an excellent effect when applied to a system for preventing image blur caused by camera shake.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a configuration overview of Embodiment 1 of a vibration detection device using an optical fiber gyro according to the present invention, and FIGS. 2(a) and (b) are implementations of the vibration detection device using an optical fiber gyro, respectively. FIG. 3 is a diagram showing a part of the configuration outline of Example 2, FIG. 3 is a diagram showing a part of the configuration outline of Example 3 of a vibration detection device using an optical fiber gyro, and FIGS. 4 and 5 are respectively FIG. 6 is a diagram showing an outline of the configuration of a vibration detection device using an optical fiber gyro according to a comparative example, and FIG. FIG. 8 is a diagram for explaining the principle of an optical fiber gyro, and is a diagram for explaining problems with the configuration of FIG. 6. 11a, llb... Optical fiber loop 12... Lens barrel 13a, 13b... Axis perpendicular to detected vibration (winding center)
21a, 21b...optical fiber loops 22a, 22
b...Optical fiber loop 25...Camera body 41...Photographing optical axis 45a, 45b...Detection section 46...Correction optical system 47a, 47b...Drive section 48...Image plane and other 4 given name

Claims (1)

[Claims] 1. In order to detect vertical shake vibration around the horizontal axis and/or lateral shake vibration around the vertical axis of the camera, the Sagnac phase difference of light in two directions propagating in opposite directions in an optical fiber loop is used. In a camera equipped with an optical fiber gyro that detects the vibration angular velocity, the optical fiber loop has an axis perpendicular to the vibration vibration plane that is the object of detection as the center of the loop shape, and a vertical axis with respect to the vibration vibration plane. A camera shake vibration detection device using an optical fiber gyro characterized by being arranged within a curved curved surface. 2. In order to detect vertical shake vibration around the horizontal axis and/or lateral shake vibration around the vertical axis of the camera, the Sagnac phase difference of the light in two directions propagating in opposite directions in the optical fiber loop is detected and the vibration angular velocity is determined. In a camera equipped with an optical fiber gyro for detecting vibration, the optical fiber loop has an axis perpendicular to the blur vibration plane to be detected as the center of the shape of the loop, and forms an oval or elliptical shape within the blur vibration plane. A camera shake vibration detection device using an optical fiber gyro. 3. In order to detect vertical shake vibration around the horizontal axis and/or lateral shake vibration around the vertical axis of the camera, the Sagnac phase difference of the light in two directions propagating in opposite directions in the optical fiber loop is detected, and the vibration angular velocity is determined. In a camera equipped with an optical fiber gyro for detecting motion, the optical fiber loop is provided in a figure 8 shape with an axis substantially parallel to the direction of vibration vibration to be detected as the center of the shape of the loop, and with respect to the vibration vibration plane. A camera shake vibration detection device using an optical fiber gyro characterized by being arranged within a curved curved surface.