1. Field of the Invention
The present invention relates to an optical apparatus having an image stabilizing device for performing vibration suppression by deflecting a light beam.
2. Related Background Art
A conventional camera having a vibration suppression function will be described below.
In recent cameras, since all the operations necessary for a photographing operation such as exposure determination, focusing, and the like are automatically performed, even a person who is not skilled in camera operations rarely makes an unsuccessful photographing operation. However, it is difficult to automatically prevent an unsuccessful photographing operation caused by a camera vibration.
Thus, in recent years, extensive studies have been made to achieve cameras, which can prevent an unsuccessful photographing operation caused by a camera vibration. In particular, cameras, which can prevent an unsuccessful photographing operation caused by a hand vibration of a photographer, have been developed and studied.
For example, a hand vibration of a camera in a photographing operation will be explained below. The hand vibration normally has a frequency of 1 Hz to 20 Hz. As a basic principle for allowing to confirm a state free from an image blur when an object is viewed through a finder of a camera even when a camera vibration occurs, and to take a photograph free from an image blur upon a shutter release operation of the camera, the camera vibration must be detected, and a correction lens must be displaced according to the detection value.
In order to achieve this object, i.e., to allow to take a photograph without causing an image blur even in the camera vibration state, the camera vibration can be detected by arranging, in a camera, a vibration sensor for detecting an angular acceleration, an angular speed, or the like, and a camera vibration detection system for electrically or mechanically integrating the sensor signal to output an angular displacement in a camera in principle. Based on this detection information, a correction optical system having a correction lens whose photographing optical axis is decentered or inclined as an optical correction member is driven, thereby performing image blur correction.
An image blur correction camera system using an angular accelerometer will be described below with reference to FIG. 10.
This system corrects an image blur caused by a camera vertical vibration 51p and a camera horizontal vibration 51y in directions of arrows 51 in FIG. 10. The system includes a lens barrel 52, angular accelerometers 53p and 53y, respectively having angular acceleration detection directions 54p and 54y, for respectively detecting angular accelerations of the camera vertical and horizontal vibrations, and integrators 55p and 55y, comprising known analog integration circuits, each for integrating and converting an angular acceleration signal into an angular displacement. A correction optical system 56 (including drivers 57p and 57y, and correction optical position sensors 58p and 58y) is driven in directions 51p and 51y in a plane perpendicular to the optical axis according to the signals output from the integrators 55p and 55y so as to decenter the photographing optical axis and to assure a stable image plane 59, thus obtaining the image blur correction effect.
In the above-mentioned case, the image blur correction is performed. However, when no image blur correction is performed, the correction optical system 56 must be electrically or mechanically fixed. When the camera is carried, if the correction optical system 56 is not fixed, there is no force for restricting the movement of the correction optical system 56 in the plane perpendicular to the optical axis. As a result, the correction optical system 56 unexpectedly swings due to a vibration by carrying, thus generating noise upon collision with other surrounding members, and damaging the correction optical system 56 and its function by collision.
Conventionally, when image blur correction is not performed for a long period of time, the correction optical system 56 is fixed not by an electrical fixing member, i.e., by driving the mechanism 56 by inputting a predetermined signal to it, but by a mechanical fixing member in terms of energy saving. When the image blur correction effect is to be obtained, the mechanical fixing member must be released.
From this viewpoint, U.S. Pat. No. 4,235,506 made a proposal for mechanically fixing and releasing a correction optical system, which swings in a telescope or a binocular, and Japanese Laid-Open Patent Application No. 61-296862 made a proposal for mechanically fixing and releasing a correction optical system, which pivots in a video camera.
However, in these prior arts, the correction optical system is fixed and released by operating an exclusive external operation member. This forces a photographer to perform cumbersome operations to fix and release the correction optical system in addition to a photographing operation.
Furthermore, when a photographer forgets to fix the correction optical system, since the correction optical system maintains an image blur correction state or electrically holds a predetermined position, electrical power is consumed, thus wasting a battery. On the other hand, when the electrical holding state is not set, the function of the correction optical system is damaged by a shock due to an unexpected vibration by, e.g., carrying of a camera.