Photography – Camera shake sensing – Having stabilization system
Reexamination Certificate
2002-06-18
2003-08-12
Perkey, W. B. (Department: 2851)
Photography
Camera shake sensing
Having stabilization system
Reexamination Certificate
active
06606457
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a device which corrects a focused image tremble of an optical device due to hand tremble and so on.
2. Description of the Related Art
Conventionally, there are some optical devices, for example a camera, which are provided with a focused image tremble correcting device for correcting a focused image tremble due to a hand tremble and so on. The applicant suggests a correction optical system driving mechanism in the Japanese Unexamined Patent Publication (Kokai) No.6-35022 or in the U.S. Pat. No. 5,305,040. The driving mechanism moves a correction optical system, which forms an imaging optical system with other optical systems, on a plane perpendicular to the optical axis of the correction optical system. The driving mechanism moves the correction optical system in a direction on the plane such that the focused image tremble can be canceled. Namely, the tremble is corrected by moving the correction optical system on the above-mentioned plane such that trembles of the imaging optical system in two directions crossing at right angles (the vertical direction and the horizontal direction) can be canceled.
In the driving mechanism suggested in the above-mentioned publication, the correction optical system is rotated along the above-mentioned plane in order to simplify the mechanical structure so that the correction optical system can be driven using a small amount of power. The driving mechanism has a structure described below.
A first rotating board is mounted on a fixed board which is fixed in the optical device, being rotatable around a first rotating shaft. A second rotating board is mounted on the first rotating board, being rotatable around a second rotating shaft. A lens supporting member, which supports the correction optical system, is provided in such a manner that the lens supporting member penetrates through the fixed board, and the first and second rotating board. The first and second rotating shafts are situated so as to be parallel to the optical axis of the correction optical system. The first and second rotating boards are respectively rotated by corresponding driving machines.
In this correcting device, as described in the above-mentioned publication, the amounts of rotation of the rotating boards are calculated based on a linear-approximation. Namely, the linear moving component of the focused image in the horizontal direction is canceled by the displacement of the first rotating board in the horizontal direction defined by the rotation of the first rotating board, and the linear moving component of the focused image tremble in the vertical direction is canceled by displacement of the second rotating board in the horizontal direction defined by the rotation of the second rotating board.
As described above, the amount each of the first and second rotating boards is driven in either the horizontal and vertical directions is controlled by the corresponding amount of rotation of the first and second rotating boards, which is calculated by using linear-approximation, with respect to each of the linear moving components of the focused image in the horizontal and vertical directions. In other words, the tremble correction is carried out by assigning an amount of rotation of one rotating board to one linear moving component. In this specification, this driving control is referred to as “pseudo-linear movement”.
However, in this mechanism, if the distance between the rotating shafts and the optical axis of the correction optical system is set short to reduce the size of the device, the error in the linear-approximation is amplified, and the accuracy of the amount each rotating board is driven is lowered.
Further, the second rotating board is mounted on the first rotating board, and the pseudo-linear movement is carried out with respect to each of the first and second rotating boards. Accordingly, with respect to one rotating board, the pseudo-linear movement is performed without considering an error generated by rotating the other rotating board, and further with respect to the other rotating board, the pseudo-linear movement is performed without considering the error generated by rotating the first rotating board. Therefore, the total error is amplified.
Accordingly, it is difficult to compact the focused image tremble correcting device, so that the overall size of the optical device cannot be reduced. Namely, though the optical device is required to be small from the viewpoints of manipulation and portability, such requirement cannot be achieved.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a focused image tremble correcting device which is simple and small, and further accurately corrects a focused image tremble.
In accordance with an aspect of the present invention, there is provided a focused image tremble correcting device comprising: a tremble detector that detects a tremble of an optical device; a correction optical system that is included in an imaging optical system of the optical device and corrects the tremble; a fixed member that is fixed in the optical device; a first rotating member that is supported on the fixed member and rotates the correction optical system around a first rotating axis which is parallel to an optical axis of the correction optical system; a second rotating member that is supported on the first rotating member and rotates the correction optical system around a second rotating axis which is parallel to the optical axis of the correction optical system; and a controller. The controller calculates a moving component for an object image in a first linear direction on a focal plane of the imaging optical system. The moving component is due to an angular tremble of the optical axis of the imaging optical system. The calculation is based on the result of the tremble detector. Further, the controller cancels the moving component in the first linear direction by controlling rotations of both the first rotating member and the second rotating member.
Preferably, the controller further calculates a moving component in a second linear direction on the focal plane, and calculates a rotational angle for each of the first and second rotating members in order to control both the first and second rotating members such that both the moving component of the object image in the first linear direction and the moving component of the object image in the second linear direction can be canceled. The first and second linear directions cross on the focal plane.
Optionally, the first linear direction and the second linear direction cross at right angles, and the intersection point of the first and second linear direction corresponds to an intersection point of the optical axis of the imaging optical system and the focal plane.
Preferably, the controller calculates the rotational angles of the first and second rotating members such that the moving component in the first linear direction, the moving component in the second linear direction, the rotational angle of the first rotating member, and the rotational angle of the second rotating member satisfy the formulas to follow.
x=K
1×(
L
2×Cos(&dgr;+&thgr;+&agr;2)+
L
1×Sin(&agr;1+&thgr;))
y=K
2×(
L
2×Sin(&dgr;+&thgr;+&agr;2)−
L
1×Cos(&agr;1+&thgr;)+
d
1)
(herein, x: moving component of the object image in the first linear direction,
y: moving component of the object image in the second linear direction,
K1: predetermined proportional coefficient,
K2: predetermined proportional coefficient,
L1: length of a straight line which connects the intersection point of the first rotating axis and the focal plane with the intersection point of the second rotating axis and the focal plane,
L2: length of a straight line which connects the intersection point of the optical axis of the correction optical system and the focal plane with the intersection point of the second rotating axis and the focal plane,
&thgr;: rotati
Greenblum & Bernstein P.L.C.
Pentax Corporation
Perkey W. B.
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